gl: add darwin/arm64 (macOS) support

Update the build constraints so that OpenGL is used both on
macOS AMD64 and ARM64, while OpenGL ES is used on iOS.
This fixes the build on M1 Macs.

For golang/go#43237.

Change-Id: Iad2d406eaf0ddbe72f221f497dd074ad0b22015e
Reviewed-on: https://go-review.googlesource.com/c/mobile/+/278779
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Hajime Hoshi <hajimehoshi@gmail.com>

Author: dmitshur

gl/work.c

@@ -356,7 +356,7 @@ uintptr_t processFn(struct fnargs* args, char* parg) {
 		glScissor((GLint)args->a0, (GLint)args->a1, (GLint)args->a2, (GLint)args->a3);
 		break;
 	case glfnShaderSource:
-#if defined(os_ios) || defined(os_osx)
+#if defined(os_ios) || defined(os_macos)
 		glShaderSource((GLuint)args->a0, (GLsizei)args->a1, (const GLchar *const *)args->a2, NULL);
 #else
 		glShaderSource((GLuint)args->a0, (GLsizei)args->a1, (const GLchar **)args->a2, NULL);

gl/work.go

@@ -7,23 +7,19 @@
 package gl
 
 /*
-#cgo ios                LDFLAGS: -framework OpenGLES
-#cgo darwin,amd64,!ios  LDFLAGS: -framework OpenGL
-#cgo darwin,arm         LDFLAGS: -framework OpenGLES
-#cgo darwin,arm64       LDFLAGS: -framework OpenGLES
-#cgo linux              LDFLAGS: -lGLESv2
-#cgo openbsd            LDFLAGS: -L/usr/X11R6/lib/ -lGLESv2
-
-#cgo android            CFLAGS: -Dos_android
-#cgo ios                CFLAGS: -Dos_ios
-#cgo darwin,amd64,!ios  CFLAGS: -Dos_osx
-#cgo darwin,arm         CFLAGS: -Dos_ios
-#cgo darwin,arm64       CFLAGS: -Dos_ios
-#cgo darwin             CFLAGS: -DGL_SILENCE_DEPRECATION
-#cgo linux              CFLAGS: -Dos_linux
-#cgo openbsd            CFLAGS: -Dos_openbsd
-
-#cgo openbsd            CFLAGS: -I/usr/X11R6/include/
+#cgo ios          LDFLAGS: -framework OpenGLES
+#cgo darwin,!ios  LDFLAGS: -framework OpenGL
+#cgo linux        LDFLAGS: -lGLESv2
+#cgo openbsd      LDFLAGS: -L/usr/X11R6/lib/ -lGLESv2
+
+#cgo android      CFLAGS: -Dos_android
+#cgo ios          CFLAGS: -Dos_ios
+#cgo darwin,!ios  CFLAGS: -Dos_macos
+#cgo darwin       CFLAGS: -DGL_SILENCE_DEPRECATION
+#cgo linux        CFLAGS: -Dos_linux
+#cgo openbsd      CFLAGS: -Dos_openbsd
+
+#cgo openbsd      CFLAGS: -I/usr/X11R6/include/
 
 #include <stdint.h>
 #include "work.h"

gl/work.h

@@ -18,7 +18,7 @@
 #include <OpenGLES/ES2/glext.h>
 #endif
 
-#ifdef os_osx
+#ifdef os_macos
 #include <OpenGL/gl3.h>
 #define GL_ES_VERSION_3_0 1
 #endif