message: Fix C++11 error assign string literal to char*
  error: ISO C++11 does not allow
  conversion from string literal to 'GLchar *' (aka 'char *') [-Werror,-Wwritable-strings]
diff: @@ -65,7 +65,7 @@ RD_TEST(GL_Queries_In_Use, OpenGLGraphicsTest)
  glAttachShader(program, vs);
  glAttachShader(program, fs);
  - GLchar *posOnly = "gl_Position";
  + const GLchar *posOnly = "gl_Position";
  glTransformFeedbackVaryings(program, 1, &posOnly, GL_INTERLEAVED_ATTRIBS);
  glLinkProgram(program);
  