Fix parallel builds w/ LTO on systems where make is not GNU make. (#13955)

tmk_core/rules.mk

@@ -359,7 +359,7 @@ BEGIN = gccversion sizebefore
 # Note the obj.txt depeendency is there to force linking if a source file is deleted
 %.elf: $(OBJ) $(MASTER_OUTPUT)/cflags.txt $(MASTER_OUTPUT)/ldflags.txt $(MASTER_OUTPUT)/obj.txt | $(BEGIN)
 	@$(SILENT) || printf "$(MSG_LINKING) $@" | $(AWK_CMD)
-	$(eval CMD=$(CC) $(ALL_CFLAGS) $(filter-out %.txt,$^) --output $@ $(LDFLAGS))
+	$(eval CMD=MAKE=$(MAKE) $(CC) $(ALL_CFLAGS) $(filter-out %.txt,$^) --output $@ $(LDFLAGS))
 	@$(BUILD_CMD)