Use $(MAKE) rather than gmake.

Node: This SHOULD pass command-line arguments to child make but doesn't/

src/sbbs3/GNUmakefile

@@ -416,7 +416,7 @@ $(MAKEUSER): \
 depend:
 	@$(DELETE) $(LIBODIR)/.depend
 	@$(DELETE) $(EXEODIR)/.depend
-	gmake BUILD_DEPENDS=1
+	$(MAKE) BUILD_DEPENDS=1
 
 # Auto-dependency files (should go in output dir, but gcc v2.9.5 puts in cwd)
 -include ./*.d