Move comment about some logic out of the shader code to reduce binary size.

PiperOrigin-RevId: 359589291
Change-Id: I3d475705ae66a7af99cdcce7f81857cb0e6f2ad8

tensorflow/lite/delegates/gpu/gl/kernels/mean.cc

@@ -143,13 +143,12 @@ void GenerateTrivialMean(const NodeShader::GenerationContext& ctx,
       {"input_data_0_h", static_cast<int>(ctx.input_shapes[0][1])},
       {"input_data_0_w", static_cast<int>(ctx.input_shapes[0][2])}};
 
-  std::string source = R"(
   // Shaders may be compiled with a precision hint mediump, which means that
   // GLSL compiler may drop the size of float data type from 32 to 16 bits.
   // If "sum" and "size" variables are 16bit floats, their values range
   // become not enough for providing a good results accuracy. That is why
   // their precision is forced to be 32bit by using highp qualifier.
-
+  std::string source = R"(
     highp vec4 sum = vec4(0.0);
     highp float size = float($input_data_0_w$ * $input_data_0_h$);
     for (int w = 0; w < $input_data_0_w$; w++) {