Fix simulator feature discovery

Fix depth clamp and texture swizzle feature discovery on simulator builds

Both of these features are not supported by the iphone simulator
and leads to crashes when used

MoltenVK/MoltenVK/GPUObjects/MVKDevice.mm

@@ -1802,7 +1802,11 @@
  if ( mvkOSVersionIsAtLeast(13.0) ) {
  _metalFeatures.mslVersionEnum = MTLLanguageVersion2_2;
  _metalFeatures.placementHeaps = mvkConfig().useMTLHeap;
+#if MVK_OS_SIMULATOR
+ _metalFeatures.nativeTextureSwizzle = false;
+#else
  _metalFeatures.nativeTextureSwizzle = true;
+#endif
  if (supportsMTLGPUFamily(Apple3)) {
  _metalFeatures.native3DCompressedTextures = true;
  }
@@ -2196,9 +2200,13 @@
  _features.dualSrcBlend = true;
  }
 
+#if MVK_OS_SIMULATOR
+ _features.depthClamp = false;
+#else
  if (supportsMTLFeatureSet(iOS_GPUFamily2_v4)) {
  _features.depthClamp = true;
  }
+#endif
 
  if (supportsMTLFeatureSet(iOS_GPUFamily3_v2)) {
  _features.tessellationShader = true;