Make the list NULL terminated.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%403833

src/video/xbios/SDL_xbios.c

@@ -522,7 +522,7 @@ static int XBIOS_VideoInit(_THIS, SDL_PixelFormat *vformat)
 		int j;
 
 		SDL_xbiosmode[i] = (xbiosmode_t **)
-			SDL_malloc(SDL_nummodes[i]*sizeof(xbiosmode_t *));
+			SDL_malloc((SDL_nummodes[i]+1)*sizeof(xbiosmode_t *));
 		if ( SDL_xbiosmode[i] == NULL ) {
 			SDL_OutOfMemory();
 			return(-1);
@@ -535,6 +535,7 @@ static int XBIOS_VideoInit(_THIS, SDL_PixelFormat *vformat)
 			}
 			SDL_memset(SDL_xbiosmode[i][j], 0, sizeof(xbiosmode_t));
 		}
+		SDL_xbiosmode[i][j] = NULL;
 
 		SDL_modelist[i] = (SDL_Rect **)
 				SDL_malloc((SDL_nummodes[i]+1)*sizeof(SDL_Rect *));