build: Use $(MAKE) instead of direct call to make

No functional changes, just make it to respect original make binary
name used to start building

Type: improvement

Change-Id: Ic8568237fbb39c6a0d3b7405a9670e9410aeb752
Signed-off-by: Renato Botelho do Couto <renato@netgate.com>
diff --git a/build/external/Makefile b/build/external/Makefile
index 046dd74..3cb7b47 100644
--- a/build/external/Makefile
+++ b/build/external/Makefile
@@ -94,7 +94,7 @@
 
 install-deb:
 ifneq ($(INSTALLED_VER),$(DEB_VER)-$(PKG_SUFFIX))
-	@make $(DEV_DEB)
+	@$(MAKE) $(DEV_DEB)
 	@sudo dpkg -i $(DEV_DEB)
 else
 	@echo "=========================================================="
@@ -175,7 +175,7 @@
 	$(MAKE) config
 else
 ifneq ($(INSTALLED_VER),)
-	make check-deb
+	$(MAKE) check-deb
 endif
 ifneq ($(INSTALLED_RPM_VER),)
 	$(MAKE) check-rpm