vo_gl: fix "gamma" equalizer setting

The "gamma" setting only changed red gamma. Fix it to change all of
red, green and blue gamma.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@32895 b3059339-0415-0410-9bf9-f77b7e298cf2

libvo/vo_gl.c

@@ -1393,6 +1393,8 @@ static int control(uint32_t request, void *data)
       if (!(eq_map[i].supportmask & (1 << use_yuv)))
         break;
       *eq_map[i].value = args->value;
+      if (strcmp(args->name, "gamma") == 0)
+        eq_rgamma = eq_ggamma = eq_bgamma = args->value;
       update_yuvconv();
       return VO_TRUE;
     }