Fix Garch opengl check, add ARC conditionals to HgiMetal.

* Note blitCmds.mm is still using the wrong MTLResource
  type on L.361, which should be MTLBuffer, but that issue
  is addressed in the following PR:
  #3226

Signed-off-by: furby™ <devs@wabi.foundation>

Author: furby-tm

pxr/imaging/garch/glPlatformContextDarwin.mm

@@ -9,7 +9,7 @@
 #include "pxr/pxr.h"
 #include "glPlatformContextDarwin.h"
 
-#if defined(PXR_OPENGL_SUPPORT_ENABLED)
+#if defined(PXR_GL_SUPPORT_ENABLED)
 #ifdef ARCH_OS_OSX
 #import <AppKit/NSOpenGL.h>
 typedef NSOpenGLContext NSGLContext;
@@ -27,7 +27,7 @@
 {
 public:
     Detail() {
-#if defined(PXR_OPENGL_SUPPORT_ENABLED)
+#if defined(PXR_GL_SUPPORT_ENABLED)
         context = [NSGLContext currentContext];
 #else
         context = nil;
@@ -82,7 +82,7 @@
 void
 GarchNSGLContextState::MakeCurrent()
 {
-#if defined(PXR_OPENGL_SUPPORT_ENABLED)
+#if defined(PXR_GL_SUPPORT_ENABLED)
 #if defined(ARCH_OS_IPHONE)
     [EAGLContext setCurrentContext:_detail->context];
 #else
@@ -95,7 +95,7 @@
 void
 GarchNSGLContextState::DoneCurrent()
 {
-#if defined(PXR_OPENGL_SUPPORT_ENABLED)
+#if defined(PXR_GL_SUPPORT_ENABLED)
 #if defined(ARCH_OS_IPHONE)
     [EAGLContext setCurrentContext:nil];
 #else

pxr/imaging/hgiMetal/blitCmds.mm

@@ -353,6 +353,7 @@
         memcpy(dst + dstOffset, src, copyOp.byteSize);
     }
 
+#if defined(ARCH_OS_OSX)
     if (!sharedBuffer &&
         [metalBuffer->GetBufferId()
              respondsToSelector:@selector(didModifyRange:)]) {
@@ -364,6 +365,7 @@
         [resource didModifyRange:range];
         ARCH_PRAGMA_POP
     }
+#endif // defined(ARCH_OS_OSX)
 }
 
 void

pxr/imaging/hgiMetal/indirectCommandEncoder.mm

@@ -115,8 +115,10 @@
 }
 
 HgiMetalIndirectCommandEncoder::~HgiMetalIndirectCommandEncoder() {
+#if !__has_feature(objc_arc)
     [_triangleTessFactors release];
     [_quadTessFactors release];
+#endif // !__has_feature(objc_arc)
 }
 
 std::string