message: Silence Metal shader compilation warnings
diff: @@ -250,12 +250,14 @@ MetalProgram::MetalProgram(id<MTLDevice> device, const Program& program) noexcep
  error:&error];
  [objcSource release];
  [options release];
  + if (library == nil) {
  if (error) {
  auto description =
  [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
  utils::slog.w << description << utils::io::endl;
  }
  - ASSERT_POSTCONDITION(library != nil, "Unable to compile Metal shading library.");
  + ASSERT_POSTCONDITION(false, "Unable to compile Metal shading library.");
  + }
  *shaderFunctions[i] = [library newFunctionWithName:@"main0"];
  