cvs libguile-ltdl and scmconfig.h

[Kevin Ryde]

Now that libguile/scmconfig.h is a generated file, I think
libguile-ltdl needs to express that it should be built before
attempting to compile libguile-ltdl.la.

Without that, raw-ltdl.c can hit /usr/include/libguile/scmconfig.h,
which is likely to be wrong (in my case the debian packaged guile
1.4).

I got some joy from adding the following to libguile-ltdl/Makefile.am

        BUILT_SOURCES = ../libguile/scmconfig.h
        ../libguile/scmconfig.h:
                cd ../libguile; $(MAKE) $(AM_MAKEFLAGS) scmconfig.h

Or alternately maybe raw-ltdl.c only really needs config.h now.  I'm
not smart enough to tell.