Makefile: option to print C compile flags

- print with no EOL the module interface flag in Makefile.modules

Makefile

@@ -1189,3 +1189,7 @@ dbschema:
 	-@echo "Build database schemas"
 	$(MAKE) -C lib/srdb1/schema
 	-@echo "Done"
+
+.PHONY: printcdefs
+printcdefs:
+	@echo -n $(C_DEFS)

Makefile.modules

@@ -307,7 +307,7 @@ endif
 
 
 printmiface:
-	@echo $(MODIFACE)
+	@echo -n $(MODIFACE)
 
 endif # ifeq($(makefile_defs),1)