Update Makefile to build on Apple Silicon

Makefile

@@ -285,6 +285,8 @@ else ifeq ($(YQ2_OSTYPE),OpenBSD)
 INCLUDE ?= -I/usr/local/include
 else ifeq ($(YQ2_OSTYPE),Windows)
 INCLUDE ?= -I/usr/include
+else ifeq ($(YQ2_OSTYPE),Darwin)
+INCLUDE ?= -I/usr/local/include -I/opt/homebrew/include
 endif
 
 # ----------
@@ -300,6 +302,8 @@ else ifeq ($(YQ2_OSTYPE),OpenBSD)
 LDFLAGS ?= -L/usr/local/lib
 else ifeq ($(YQ2_OSTYPE),Windows)
 LDFLAGS ?= -L/usr/lib
+else ifeq ($(YQ2_OSTYPE),Darwin)
+LDFLAGS ?= -L/usr/local/lib -L/opt/homebrew/lib
 endif
 
 # Link address sanitizer if requested.
@@ -409,7 +413,17 @@ ref_gl4:
 release/ref_gl4.dll : GLAD_INCLUDE = -Isrc/client/refresh/gl4/glad/include
 release/ref_gl4.dll : LDFLAGS += -shared
 
-else # not Windows or Darwin - macOS doesn't support OpenGL 4.6
+else ifeq ($(YQ2_OSTYPE), Darwin)
+
+ref_gl4:
+	@echo "===> Building ref_gl4.dylib"
+	${Q}mkdir -p release
+	$(MAKE) release/ref_gl4.dylib
+
+release/ref_gl4.dylib : GLAD_INCLUDE = -Isrc/client/refresh/gl4/glad/include
+release/ref_gl4.dylib : LDFLAGS += -shared
+
+else # not Windows or Darwin
 
 ref_gl4:
 	@echo "===> Building ref_gl4.so"
@@ -485,6 +499,11 @@ release/ref_gl4.dll : $(REFGL4_OBJS)
 	${Q}$(CC) $(LDFLAGS) $(REFGL4_OBJS) $(LDLIBS) $(DLL_SDLLDFLAGS) -o $@
 	$(Q)strip $@
 
+else ifeq ($(YQ2_OSTYPE), Darwin)
+release/ref_gl4.dylib : $(REFGL4_OBJS)
+	@echo "===> LD $@"
+	${Q}$(CC) $(LDFLAGS) $(REFGL4_OBJS) $(LDLIBS) $(SDLLDFLAGS) -o $@
+
 else
 release/ref_gl4.so : $(REFGL4_OBJS)
 	@echo "===> LD $@"

README.md

@@ -15,6 +15,14 @@ Type `make` to compile the library. If the compilation is successfull,
 the library can be found under *release/ref_gl4.dll* (Windows) or
 *release/ref_gl4.so* (unixoid systems).
 
+## Supported platforms
+
+* FreeBSD
+* Linux
+* NetBSD
+* OpenBSD
+* Windows
+
 ## Usage
 
 Copy the library next to your Yamagi Quake II executable. You can select