Reenable xbios usage to get relative mouse motion

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402077

src/video/gem/SDL_gemvideo.c

@@ -197,9 +197,9 @@ static SDL_VideoDevice *GEM_CreateDevice(int devindex)
 	if (!(device->hidden->use_dev_mouse)) {
 		vectors_mask |= ATARI_XBIOS_MOUSEEVENTS;	/* XBIOS mouse events */
 	}
-	if (Getcookie(C_MiNT, &dummy)==C_FOUND) {
+/*	if (Getcookie(C_MiNT, &dummy)==C_FOUND) {
 		vectors_mask = 0;
-	}
+	}*/
 
 	SDL_AtariXbios_InstallVectors(vectors_mask);