Unbreak build when building without GMP support.

Add support for a new preprocessor macro EMACS_MODULE_HAVE_MPZ_T to
emacs-module.h.  If this macro is defined, assume that mpz_t is
already defined and don’t include gmp.h.

Don’t document the new macro for now, as it’s unclear whether we want
to support this in modules outside the Emacs tree.

* src/emacs-module.h.in: Allow user to prevent inclusion of gmp.h.

* src/emacs-module.c: Use mini-gmp if GMP is unavailable.  Don’t
include gmp.h.

* src/lisp.h: Don’t require gmp.h.  It’s not needed for lisp.h.

* test/Makefile.in (GMP_LIB, GMP_OBJ): New variables.
($(test_module)): Use them.

* test/data/emacs-module/mod-test.c: Use mini-gmp if GMP is unavailable.

2 files changed, 9 insertions, 3 deletions

diff --git a/test/Makefile.in b/test/Makefile.in
index 2282ccd951c..ec20a427ba5 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -257,6 +257,7 @@ endif
 HYBRID_MALLOC = @HYBRID_MALLOC@
 LIBEGNU_ARCHIVE = ../lib/lib$(if $(HYBRID_MALLOC),e)gnu.a
 GMP_LIB = @GMP_LIB@
+GMP_OBJ = $(if @GMP_OBJ@, ../src/@GMP_OBJ@)
 
 # Note: emacs-module.h is generated from emacs-module.h.in, hence we
 # look in ../src, not $(srcdir)/../src.
@@ -269,7 +270,7 @@ src/emacs-module-tests.log: $(test_module)
 $(test_module): $(test_module:${SO}=.c) ../src/emacs-module.h $(LIBEGNU_ARCHIVE)
         $(AM_V_at)${MKDIR_P} $(dir $@)
         $(AM_V_CCLD)$(CC) -shared $(CPPFLAGS) $(MODULE_CFLAGS) $(LDFLAGS) \
-          -o $@ $< $(LIBEGNU_ARCHIVE) $(GMP_LIB)
+          -o $@ $< $(LIBEGNU_ARCHIVE) $(GMP_LIB) $(GMP_OBJ)
 endif
 
 ## Check that there is no 'automated' subdirectory, which would
diff --git a/test/data/emacs-module/mod-test.c b/test/data/emacs-module/mod-test.c
index 8ac08f71534..b7007bd80ff 100644
--- a/test/data/emacs-module/mod-test.c
+++ b/test/data/emacs-module/mod-test.c
@@ -27,11 +27,16 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <string.h>
 #include <time.h>
 
+#ifdef HAVE_GMP
+#include <gmp.h>
+#else
+#include "mini-gmp.h"
+#define EMACS_MODULE_HAVE_MPZ_T
+#endif
+
 #define EMACS_MODULE_GMP
 #include <emacs-module.h>
 
-#include <gmp.h>
-
 #include "timespec.h"
 
 int plugin_is_GPL_compatible;