message: Add some error handling for a std::system call.
diff: @@ -16476,7 +16476,11 @@ extern "C" __declspec( dllimport ) FARPROC __stdcall GetProcAddress( HINSTANCE h
  #if defined( CLANG_FORMAT_EXECUTABLE )
  std::cout << "VulkanHppGenerator: Formatting using ";
  std::string commandString = "\"" CLANG_FORMAT_EXECUTABLE "\" --version ";
  - (void)std::system( commandString.c_str() );
  + int ret = std::system( commandString.c_str() );
  + if ( ret != 0 )
  + {
  + std::cout << "VulkanHppGenerator: failed to determine clang_format version with error <" << ret << ">\n";
  + }
  #endif
  std::cout << "VulkanHppGenerator: Parsing " << filename << std::endl;
  