* libguile/Makefile.am (WHIPPET_EMBEDDER_H): Define this variable
instead of using -include; otherwise we don't get the chance to set
_LARGEFILE64_SOURCE before including Whippet files.
(AM_CPPFLAGS): Simplify.
(libguile_@GUILE_EFFECTIVE_VERSION@_la_DEPENDENCIES): Explicitly add
libwhippet.la as a dependency.
(noinst_HEADERS): Add gc-internal.h
* libguile/gc-internal.h: New file.
* libguile/gc.c: Include gc-internal.h.