fix unreferenced local variable warning

includes/learnopengl/shader.h

@@ -61,8 +61,6 @@ public:
         const char * fShaderCode = fragmentCode.c_str();
         // 2. compile shaders
         unsigned int vertex, fragment;
-        int success;
-        char infoLog[512];
         // vertex shader
         vertex = glCreateShader(GL_VERTEX_SHADER);
         glShaderSource(vertex, 1, &vShaderCode, NULL);