Add macOS aarch64 (Apple Silicon) build support

- Add __aarch64__ and __arm__ cases to the macOS architecture block in
  q_platform.h (the existing aarch64 support was only in the Linux block)
- Normalize arm/arm64 to aarch64 in the Makefile since uname -p returns
  'arm' on Apple Silicon
- Only set HAVE_VM_COMPILED on architectures that have a bytecode
  compiler (x86, x86_64, ppc, ppc64) so aarch64 falls back to the
  interpreter
- Add -arch arm64 optimization flag for darwin/aarch64

Author: jackharrhy

Makefile

@@ -80,6 +80,13 @@ ifeq ($(COMPILE_ARCH),axp)
   COMPILE_ARCH=alpha
 endif
 
+ifeq ($(COMPILE_ARCH),arm)
+  COMPILE_ARCH=aarch64
+endif
+ifeq ($(COMPILE_ARCH),arm64)
+  COMPILE_ARCH=aarch64
+endif
+
 ifndef ARCH
 ARCH=$(COMPILE_ARCH)
 endif
@@ -458,7 +465,9 @@ else # ifeq Linux
 #############################################################################
 
 ifeq ($(PLATFORM),darwin)
-  HAVE_VM_COMPILED=true
+  ifneq ($(findstring $(ARCH),x86 x86_64 ppc ppc64),)
+    HAVE_VM_COMPILED=true
+  endif
   LIBS = -framework Cocoa
   CLIENT_LIBS=
   RENDERER_LIBS=
@@ -482,6 +491,9 @@ ifeq ($(PLATFORM),darwin)
   ifeq ($(ARCH),x86_64)
     OPTIMIZEVM += -arch x86_64 -mfpmath=sse
   endif
+  ifeq ($(ARCH),aarch64)
+    OPTIMIZEVM += -arch arm64
+  endif
 
   # When compiling on OSX for OSX, we're not cross compiling as far as the
   # Makefile is concerned, as target architecture is specified as a compiler

code/qcommon/q_platform.h

@@ -161,6 +161,12 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #define idx64 1
 #define ARCH_STRING "x86_64"
 #define Q3_LITTLE_ENDIAN
+#elif defined __aarch64__
+#define ARCH_STRING "aarch64"
+#define Q3_LITTLE_ENDIAN
+#elif defined __arm__
+#define ARCH_STRING "arm"
+#define Q3_LITTLE_ENDIAN
 #endif
 
 #define DLL_EXT ".dylib"