macOS/iOS fixes plus other generic fixes for clang and validation warnings (#1117)

* Fix clang Objective-C++ flags for macOS command line builds

* Fix getAssetPath() and getShaderBasePath() for macOS command line builds

* Protect debugUtilsMessageCallback() from failing when pMessageIdName is NULL

* Fix a few clang function override and mismatched type warnings

* Fix validation layer warnings on exit for computeraytracing example

* Fix regression in text visibility toggle for textOverlay example

* Support VK_USE_PLATFORM_METAL_EXT vs. deprecated VK_USE_PLATFORM_MACOS_MVK / DVK_USE_PLATFORM_IOS_MVK

* Check dynamic state features before enabling capabilities in dynamicstate example

* Fix vkCmdDraw() vertexCount argument (PARTICLE_COUNT) in particlesystem example

* Update examples list and restore benchmarking script (to top level)

* Fix validation warning in descriptorindexing example

* Fix device max recursion depth validation warnings in ray tracing examples

* Fix OpenMP build settings for texture3d example on all platforms

* Update and simplify build instructions for macOS

* Update CI script with correct library path for libomp on macOS x86_64

* Update CI scipt to install libomp prior to macOS builds

* Trying one more time to get the CI script working for macOS libomp

* Fix vertexCount argument using calculated size in particlesystem example

* Fix combined image descriptor offset calculation in descriptorbuffer example

* macOS: Support non-system level Vulkan SDK installs, with fallback to MoltenVK library

BUILD.md

@@ -50,28 +50,25 @@ If you want to build and install on a connected device or emulator image, run ``
 
 If you want to build it through [Android Studio](https://developer.android.com/studio), open project folder ```android``` in Android Studio.
 
-### <img src="./images/applelogo.png" alt="" height="32px"> [iOS and macOS](xcode/)
+### <img src="./images/applelogo.png" alt="" height="32px"> macOS and iOS
 
-**Note:** Running these examples on Mac OS and iOS requires [**MoltenVK**](https://github.com/KhronosGroup/MoltenVK) and a device that supports the *Metal* api.
+**Note:** Running these examples on macOS and iOS requires [**MoltenVK**](https://github.com/KhronosGroup/MoltenVK) and a device that supports the *Metal* api.
 
-#### MacOS
-Install Libomp with:
--brew install libomp
-find the path
--brew --prefix libomp  
-use the path from the above command to populate the path in the -DOpenMP_C_FLAGS, -DOpenMP_omp_LIBRARY & -DOpenMP_CXX_FOUND statement below
+#### macOS
+Download the most recent Vulkan SDK using:
+```curl -O https://sdk.lunarg.com/sdk/download/latest/mac/vulkan_sdk.dmg```
 
-Download Vulkan SDK and install it note the path as this will need to be configure in Xcode
-curl -O https://sdk.lunarg.com/sdk/download/latest/mac/vulkan_sdk.dmg  
+Open **vulkan_sdk.dmg** and install the Vulkan SDK with *System Global Installation* selected.
 
-Open vulkan_sdk.dmg and install Vulkan SDK
-Navigate to the Vulkan SDK folder and run 'python install_vulkan.py'
+Install **libomp** from [homebrew](https://brew.sh) using:
+```brew install libomp```
 
-Use the provided CMakeLists.txt with [CMake](https://cmake.org) to generate a build configuration for your favorite IDE or compiler, e.g.:
-```
-Example of cmake with libraries defined
-cmake -G "Xcode" -DOpenMP_C_FLAGS=/usr/local/opt/libomp -DOpenMP_omp_LIBRARY=/usr/local/opt/libomp -DOpenMP_CXX_FOUND=/usr/local/opt/libomp
-```
+Find the **libomp** path prefix using:
+```brew --prefix libomp```
 
+Use the **libomp** path prefix to adjust the path for ```-DOpenMP_omp_LIBRARY=``` in the cmake command below.
 
+Use [CMake](https://cmake.org) to generate a build configuration for Xcode or your preferred build method (e.g. Unix Makefiles or Ninja).
 
+Example of cmake generating for Xcode with **libomp** path defined for homebrew on Apple Silicon:
+```cmake -G "Xcode" -DOpenMP_omp_LIBRARY=/opt/homebrew/opt/libomp/lib/libomp.dylib```