only SDL_Flip is critical, not the check

mandelbrot-openmp.c

@@ -53,9 +53,9 @@ void drawmandelbrot(SDL_Surface * surface) {
     pixels[i] = color;
 
     /* Update the screen every 10 lines. */
+    if (y % 10 == 0 && x == 0) {
       #pragma omp critical
       {
-      if (y % 10 == 0 && x == 0) {
         SDL_Flip(surface);
       }
     }