Small performance cleanup.

PiperOrigin-RevId: 304690776

Author: tensorflower-gardener

tensorflow_graphics/rendering/opengl/gl_program.cc

@@ -76,7 +76,7 @@ tensorflow::Status Program::Create(
 
   // Compile and attach the input shaders to the program.
   std::vector<Cleanup<std::function<void()>>> shader_cleanups;
-  for (auto shader : shaders) {
+  for (const auto& shader : shaders) {
     GLuint shader_idx;
     TF_RETURN_IF_ERROR(CompileShader(shader.first, shader.second, &shader_idx));
     std::function<void()> compile_cleanup = [shader_idx]() {