Add Raspberry Pi to OpenGL ES2 makefile

demo/sdl_opengles2/Makefile

@@ -18,7 +18,10 @@ $(BIN): prepare
 	$(CC) $(SRC) $(CFLAGS) -o bin/$(BIN) $(LIBS)
 
 web: prepare
-	emcc $(SRC) -Os -s USE_SDL=2 -o bin/index.html 
+	emcc $(SRC) -Os -s USE_SDL=2 -o bin/index.html
+
+rpi: prepare
+	$(CC) $(SRC) $(CFLAGS) -o bin/$(BIN) `PKG_CONFIG_PATH=/opt/vc/lib/pkgconfig/ pkg-config --cflags --libs bcm_host brcmglesv2` `/usr/local/bin/sdl2-config --libs --cflags`
 
 prepare:
 	@mkdir -p bin