Merge GH interface library into libguile.
* gh.h, gh_data.c, gh_eval.c, gh_funcs.c, gh_init.c, gh_io.c,
gh_list.c, gh_predicates.c, gh_test_c, gh_test_c.c, gh_test_repl,
gh_test_repl.c: New files.
* Makefile.am (libguile_la_SOURCES): Add gh_data.c, gh_eval.c,
gh_funcs.c, gh_init.c, gh_io.c, gh_list.c, gh_predicates.c. Move
_scm.h to ...
(EXTRA_libguile_la_SOURCES): ... here.
(pkginclude_HEADERS): Add variable, to get gh.h installed.
(THREAD_LIBS, check_ldadd, check_PROGRAMS, gh_test_c_SOURCES,
gh_test_c_LDADD, gh_test_repl_SOURCES, gh_test_repl_LDADD):
New variables, describing how to build the gh test programs.
* configure.in: Check for -lm, -lsocket, -lnsl; we need this to
build the test programs, and we probably should have been linking
libguile.la against them all along, to support AIX shared libs.
Add cflags for threads to CFLAGS; add libs for threads to new
variable THREAD_LIBS, used in Makefile.am.
* ChangeLog-gh: log from old `gh' subdirectory.
* Makefile.in, configure, scmconfig.h.in: Rebuilt.
