title: Cannot use SDL_gfxPrimitive
body: <p>I´m trying to use the filledCircleRGBA function from the _gfxPrimitive lib from SDL2, but it says 'fatal error:SDL2_gfxPrimitives.h: No such file or directory</p>
  
  <p>I have both includes and I use -lSDL2 and -lSDL2_gfx on the command line</p>
  
  <pre><code>#include &lt;SDL.h&gt;    
  #include &lt;SDL2_gfxPrimitives.h&gt;
  
  int main() {
      SDL_Window* g_pWindow = NULL;
      filledCircleRGBA(g_pWindow, 2, 4, 4, 255, 255, 255, 255);
  
  return 0;
  }
  </code></pre>
  
  <p>Why can´t I use _gfxPrimitives functionalities? I have the -dev SDL2 installed, so it should have all the libs</p>