document some more libtool variables

[Ralf Wildenhues]

OK to apply this to HEAD, to document some more of the libtool
script variables?

Cheers,
Ralf

        * doc/libtool.texi (Tags): Mention `FC'.
        (libtool script contents) <CC>: Specify more precisely as the
        compiler of the current tag.
        <LTCC, LTCFLAGS, build, build_alias, build_os, host_alias,
        host_os, macro_version, macro_revision, max_cmd_len>:
        Document these variables.

Index: doc/libtool.texi
===================================================================
RCS file: /cvsroot/libtool/libtool/doc/libtool.texi,v
retrieving revision 1.209
diff -u -r1.209 libtool.texi
--- doc/libtool.texi    30 Jan 2006 20:24:37 -0000      1.209
+++ doc/libtool.texi    14 Feb 2006 22:24:00 -0000
@@ -2510,6 +2511,7 @@
 @item C++              @tab CXX
 @item Java             @tab GCJ
 @item Fortran 77       @tab F77
address@hidden Fortran          @tab FC
 @item Windows Resource @tab RC
 @end multitable
@@ -5131,7 +5133,8 @@
 @end defvar
 
 @defvar CC
-The name of the C compiler used to configure libtool.
+The name of the compiler used to configure libtool.  This will always
+contain the compiler for the current language (@pxref{Tags}).
 @end defvar
 
 @defvar ECHO
@@ -5145,6 +5148,12 @@
 linking and possibly shared libraries.
 @end defvar
 
address@hidden LTCC
address@hidden LTCFLAGS
+The name of the C compiler and C compiler flags used to configure
+libtool.
address@hidden defvar
+
 @defvar NM
 The name of a BSD- or MS-compatible program that produces listings of
 global symbols.
@@ -5213,6 +5222,13 @@
 instead of @var{soname}.
 @end defvar
 
address@hidden build
address@hidden build_alias
address@hidden build_os
+Set to the specified and canonical names of the system that libtool was
+built on.
address@hidden defvar
+
 @defvar build_libtool_libs
 Whether libtool should build shared libraries on this system.  Set to
 @samp{yes} or @samp{no}.
@@ -5372,8 +5382,9 @@
 
 @defvar host
 @defvarx host_alias
-For information purposes, set to the specified and canonical names of
-the system that libtool was configured for.
address@hidden host_os
+Set to the specified and canonical names of the system that libtool was
+configured for.
 @end defvar
 
 @defvar include_expsyms
@@ -5413,6 +5424,18 @@
 linking.
 @end defvar
 
address@hidden macro_version
address@hidden macro_revision
+The release and CVS revision from which the libtool.m4 macros were
+taken.  This is used to ensure that macros and @code{ltmain.sh}
+correspond to the same Libtool version.
address@hidden defvar
+
address@hidden max_cmd_len
+The approximate longest command line that can be passed to @samp{$SHELL}
+without being truncated, as computed by @samp{LT_CMD_MAX_LEN}.
address@hidden defvar
+
 @defvar need_lib_prefix
 Whether we can @code{dlopen} modules without a @samp{lib} prefix.
 Set to @samp{yes} or @samp{no}.  By default, it is @samp{unknown}, which