message: build: Add MacOS Specific Code to DynamicLoader
  Added MacOS specific code to the DynamicLoader class.
  vkCubepp in KhronosGroup/Vulkan-Tools requires this change to
  build on MacOS.
diff: @@ -1048,6 +1048,8 @@ void VulkanHppGenerator::appendDispatchLoaderDynamic(std::string & str)
  {
  #if defined(__linux__)
  m_library = dlopen( "libvulkan.so", RTLD_NOW | RTLD_LOCAL );
  +#elif defined(__APPLE__)
  + m_library = dlopen( "libvulkan.dylib", RTLD_NOW | RTLD_LOCAL );
  #elif defined(_WIN32)
  m_library = LoadLibrary( "vulkan-1.dll" );
  #else
  @@ -1068,7 +1070,7 @@ void VulkanHppGenerator::appendDispatchLoaderDynamic(std::string & str)
  {
  if ( m_library )
  {
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  dlclose( m_library );
  #elif defined(_WIN32)
  FreeLibrary( m_library );
  @@ -1079,7 +1081,7 @@ void VulkanHppGenerator::appendDispatchLoaderDynamic(std::string & str)
  template <typename T>
  T getProcAddress( const char* function ) const
  {
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  return (T)dlsym( m_library, function );
  #elif defined(_WIN32)
  return (T)GetProcAddress( m_library, function );
  @@ -1090,7 +1092,7 @@ void VulkanHppGenerator::appendDispatchLoaderDynamic(std::string & str)
  private:
  bool m_success;
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  void *m_library;
  #elif defined(_WIN32)
  HMODULE m_library;
  @@ -5147,7 +5149,7 @@ static const std::string constExpressionArrayCopy = R"(
  # define VULKAN_HPP_ASSERT assert
  #endif
  -#if defined(__linux__)
  +#if defined(__linux__) || defined(__APPLE__)
  # include <dlfcn.h>
  #endif
  )";
  