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

.github/workflows/build.yml

@@ -56,8 +56,9 @@ jobs:
               --root ~/VulkanSDK/latest --accept-licenses --default-answer --confirm-command install
           cd ~/VulkanSDK/latest
           sudo python ./install_vulkan.py
+          brew install libomp
           brew --prefix libomp 
       - name: Build
         run: |
-          cmake -G "Xcode" -DOpenMP_C_FLAGS=/usr/local/opt/libomp -DOpenMP_omp_LIBRARY=/usr/local/opt/libomp -DOpenMP_CXX_FOUND=/usr/local/opt/libomp
+          cmake -G "Xcode" -DOpenMP_omp_LIBRARY=/usr/local/opt/libomp/lib/libomp.dylib
           cmake --build .