Funny behavior from autoconf

[Brian Lloyd]

The following Makefile.am does not work as expected.  This is a stripped
down version of the complete makefile.  It still shows the same problem
as the complete file, which is more than twice as large. 

The way it works, one of either BOOST1_33, BOOST1_31, or BOOST1_28 will
be defined.  The am__vegastrike_SOURCES_DIST is properly built by
autoconf and shows the files from all three options.  The
vegastrike_SOURCES variable also comes out correctly.  However, the
vegastrike_OBJECTS variable does not contain ANY of the optional
sources.  Why would autoconf be able to define the SOURCES_DIST
correctly, the _SOURCES correctly, but mess up the _OBJECTS variable?
There are actually three programs that use the BOOSTSOURCES statically
linked into themselves, and all three have the same problem.  It's
because there are three programs that the variable BOOSTSOURCES is used.

---- Makefile.am follows -----
ACLOCAL_AMFLAGS = -I m4scripts

#BOOST_BEGIN -- Data between the BOOST_AUTO and BOOST_END tags is auto
generated.
BOOSTSOURCES = 
if BOOST1_33
BOOSTSOURCES += \
        "boost/1_33/src/list.cpp" \
        "boost/1_33/src/module.cpp" \
        "boost/1_33/src/tuple.cpp" 
endif BOOST1_33
if BOOST1_31
BOOSTSOURCES += \
        "boost/1_31/src/list.cpp" \
        "boost/1_31/src/module.cpp" \
        "boost/1_31/src/aix_init_module.cpp" \
        "boost/1_31/src/tuple.cpp" 
endif BOOST1_31
if BOOST1_28
BOOSTSOURCES += \
        "boost/1_28/src/module.cpp" \
        "boost/1_28/src/converter/type_id.cpp" \
        "boost/1_28/src/classes.cpp" \
        "boost/1_28/src/conversions.cpp" 
endif BOOST1_28
#BOOST_END -- Data between the BOOST_AUTO and BOOST_END tags is auto
generated.

bin_PROGRAMS=vegastrike

vegastrike_LDADD =                              \
src/networking/netserver_devices.o              \
src/networking/libnetclient.a                   \
src/networking/lowlevel/libnetlowlevel.a \
src/cmd/script/script_call_briefing.o \
src/cmd/script/libscript.a                              \
src/cmd/script/c_alike/libc_alike.a \
src/python/briefing_wrapper.o                   \
src/cmd/libcmd.a                                                \
src/cmd/base_init.o                                     \
src/python/libpython.a                                  \
src/gfx/libgfx.a                                                \
src/gldrv/libgldrv.a                                    \
src/cmd/ai/libai.a                                              \
src/gui/libgui.a                                                \
src/networking/libnet.a                                 \
src/cmd/collide/libcollide.a                    \
src/gfx/nav/libnav.a                                    \
src/aldrv/libaldrv.a                                    \
-lz

libroot =               \
        src/command.h                   \
        src/command.cpp                         \
        src/ship_commands.h                     \
        src/ship_commands.cpp           \
        src/mmorpgclient.h                      \
        src/mmorpgclient.cpp            \
        src/rendertext.h                        \
        src/rendertext.cpp                      \
        src/debug_vs.h                  \
        src/debug_vs.cpp                        \
        src/gfxlib.h                    \
        src/gfxlib_struct.h                     \
        src/gfxlib_struct.cpp           \
        src/linecollide.h                       \
        src/in_joystick.cpp                     \
        src/in_joystick.h                       \
        src/force_feedback.cpp          \
        src/force_feedback.h            \
        src/faction_util.cpp            \
        src/in_kb.cpp                           \
        src/in_kb.h                                     \
        src/in_sdl.cpp                          \
        src/in_mouse.cpp                        \
        src/in_mouse.h                          \
        src/in_main.cpp                         \
        src/in_main.h                           \
        src/in_handler.cpp                      \
        src/in_handler.h                        \
        src/main_loop.h                         \
        src/main_loop.cpp                       \
        src/physics.h                           \
        src/physics.cpp                         \
        src/resizable.h                         \
        src/star_system_jump.cpp  \
        src/star_system.cpp             \
        src/star_system.h                       \
        src/universe.cpp                        \
        src/universe.h                          \
        src/universe_util.h                     \
        src/universe_util.cpp           \
        src/config_xml.cpp                      \
        src/config_xml.h                        \
        src/profile.h                           \
        src/audiolib.h                          \
        src/macosx_math.cpp                     \
        src/macosx_math.h                       \
        src/cg_global.cpp

librootgeneric =                                \
        src/vsfilesystem.cpp                    \
        src/vsfilesystem.h                              \
        src/posh.cpp                                    \
        src/posh.h                                              \
        src/stardate.cpp                                \
        src/stardate.h                                  \
        src/star_system_xml.cpp                 \
        src/star_system_generic.cpp  \
        src/star_system_generic.h               \
        src/universe_generic.cpp                \
        src/universe_generic.h                  \
        src/universe_util_generic.cpp \
        src/universe_util_generic.h \
        src/galaxy.cpp                                  \
        src/galaxy_xml.cpp                              \
        src/galaxy_xml.h                                \
        src/galaxy_gen.cpp                              \
        src/galaxy_gen.h                                \
        src/faction_generic.cpp                 \
        src/faction_generic.h                   \
        src/hashtable.h                                 \
        src/hashtable.cpp                               \
        src/configxml.cpp                               \
        src/configxml.h                                 \
        src/easydom.cpp                                 \
        src/easydom.h                                   \
        src/xml_serializer.cpp                  \
        src/xml_serializer.h                    \
        src/xml_support.h                               \
        src/xml_support.cpp                             \
        src/lin_time.cpp                                \
        src/lin_time.h                                  \
        src/endianness.cpp                              \
        src/endianness.h                                \
        src/file_main.h                                 \
        src/in.h                                                \
        src/faction_util_generic.cpp \
        src/load_mission.cpp                    \
        src/savegame.cpp                                \
        src/savegame.h                                  \
        src/vegastrike.h                                \
        src/pk3.cpp                                             \
        src/pk3.h                                               \
        src/vs_globals.cpp


vegastrike_SOURCES =            \
        $(librootgeneric) $(libroot) \
        $(BOOSTSOURCES) \
        src/main.cpp