Respect build flags set by ports

--- Makefile.orig	Sun Feb  7 21:44:01 2021
+++ Makefile	Thu Feb 11 08:51:28 2021
@@ -1,19 +1,19 @@
 
 all:
-	ruby ./rebuild-fcache.rb
+	$(RUBY) ./rebuild-fcache.rb
 	cd deps/nanovg/src   && $(CC) nanovg.c -c -fPIC
 	$(AR) rc deps/libnanovg.a deps/nanovg/src/*.o
 	cd deps/mruby-file-stat/src && ../configure
 	cd src/osc-bridge    && make lib
 #	cd mruby             && UI_HOTLOAD=1 MRUBY_CONFIG=../build_config.rb rake
-	cd mruby             && MRUBY_CONFIG=../build_config.rb rake
+	cd mruby             && MRUBY_CONFIG=../build_config.rb $(RAKE)
 	$(CC) -shared -o libzest.so `find mruby/build/host -type f | grep -v mrbc | grep -e "\.o$$" | grep -v bin` ./deps/libnanovg.a \
 		./deps/libnanovg.a \
 		src/osc-bridge/libosc-bridge.a \
-		`pkg-config --libs libuv` -lm -lX11 -lGL -lpthread
+		`pkg-config --libs libuv` -lm $(LDFLAGS) -lX11 -lGL -lpthread
 	$(CC) test-libversion.c deps/pugl/pugl/pugl_x11.c \
 		  -DPUGL_HAVE_GL \
-		  -ldl -o zest -lX11 -lGL -lpthread -I deps/pugl -std=gnu99 -Wno-trigraphs
+		  -o zest $(CFLAGS) $(LDFLAGS) -lX11 -lGL -lpthread -I deps/pugl -std=gnu99 -Wno-trigraphs
 
 osx: deps/libuv.a
 	ruby ./rebuild-fcache.rb
@@ -119,8 +119,8 @@ test:
 	cd mruby &&  MRUBY_CONFIG=../build_config.rb rake test
 
 rtest:
-	cd src/mruby-qml-parse && ruby test-non-mruby.rb
-	cd src/mruby-qml-spawn && ruby test-non-mruby.rb
+	cd src/mruby-qml-parse && $(RUBY) test-non-mruby.rb
+	cd src/mruby-qml-spawn && $(RUBY) test-non-mruby.rb
 
 run: ## Run the toolkit
 	./zest osc.udp://127.0.0.1:1337