Fix the build issue with gperf

GPerf seems not allowing the empty lines though, current recipes are supposed to drop them.
but seems not working on some env.
So taking the proper way to do that instead of incompatible things against platforms.

src/Makefile.am

@@ -111,10 +111,10 @@ fcobjshash.gperf: Makefile stamp-fcobjshash.gperf
 stamp-fcobjshash.gperf: fcobjshash.gperf.h fcobjs.h
 	$(AM_V_GEN) $(CPP) -I$(top_srcdir) $(CPPFLAGS) $< | \
 	$(SED) 's/^ *//;s/ *, */,/' | \
-	$(GREP) '^[^#]' | \
 	awk ' \
 		/CUT_OUT_BEGIN/ { no_write=1; next; }; \
 		/CUT_OUT_END/ { no_write=0; next; }; \
+		/^$$/||/^#/ { next; }; \
 		{ if (!no_write) print; next; }; \
 	' - > $@.tmp && \
 	mv -f $@.tmp fcobjshash.gperf && touch $@ || ( $(RM) $@.tmp && false )