Export Py_GetBuildInfo to enable stable ABI

previously for some reason `Py_GetBuildInfo` wasn't exported
and it failed some tests. Not sure how it doesn't fail on
other platforms.

Author: naveen521kk

Makefile.pre.in

@@ -1726,7 +1726,7 @@ Modules/getbuildinfo.o: $(PARSER_OBJS) \
 		$(MODOBJS) \
 		$(DTRACE_OBJS) \
 		$(srcdir)/Modules/getbuildinfo.c
-	$(CC) -c $(PY_CORE_CFLAGS) \
+	$(CC) -c $(PY_BUILTIN_MODULE_CFLAGS) \
 	      -DGITVERSION="\"`LC_ALL=C $(GITVERSION)`\"" \
 	      -DGITTAG="\"`LC_ALL=C $(GITTAG)`\"" \
 	      -DGITBRANCH="\"`LC_ALL=C $(GITBRANCH)`\"" \

Modules/getbuildinfo.c

@@ -41,7 +41,7 @@ static char buildinfo[50 + sizeof(GITVERSION) +
                       ((sizeof(GITTAG) > sizeof(GITBRANCH)) ?
                        sizeof(GITTAG) : sizeof(GITBRANCH))];
 
-const char *
+PyAPI_FUNC(const char *)
 Py_GetBuildInfo(void)
 {
     if (initialized) {