Suppressed another GL_FRONT drawing routine, causing potential slowdowns

for some configs. This was an old hack for sgi's, so I've put it behind an
ifdef for sgi and suns now.

Test if blender still works by switching screens, and check for the borders
between the blender area windows. These should draw all nice empty/black.

source/blender/src/editscreen.c

@@ -113,7 +113,6 @@
 static void testareas(void);
 static void area_autoplayscreen(void);
 static void wait_for_event(void);
-static void drawscreen(void);
 
 
 /* ********* Globals *********** */
@@ -1115,6 +1114,7 @@ static void drawscreen(void)
 	}
 	
 	/* this double draw patch seems to be needed for certain sgi's (octane, indigo2) */
+#if defined(__sgi) || defined(__sun__) || defined( __sun ) || defined (__sparc) || defined (__sparc__)
 	glDrawBuffer(GL_FRONT);
 	
 	sa= G.curscreen->areabase.first;
@@ -1124,6 +1124,7 @@ static void drawscreen(void)
 	}
 	
 	glDrawBuffer(GL_BACK);
+#endif
 }
 
 static void screen_dispatch_events(void) {