use -variable instead of static g++

Makefile

@@ -5,7 +5,7 @@ default: main
 
 main: src/main.cpp
 	mkdir -p bin
-	g++ $(CXXFLAGS) -o bin/main src/main.cpp
+	$(CXX) $(CXXFLAGS) -o bin/main src/main.cpp
 
 fuzz_main: src/main.cpp
 	mkdir -p bin