fix warning

src/mesa/drivers/x11/xm_tri.c

@@ -1617,10 +1617,9 @@ get_triangle_func(GLcontext *ctx)
          }
       }
    }
+#endif /* CHAN_BITS == 8 */
 
-#else
    return (swrast_tri_func) NULL;
-#endif /* CHAN_BITS == 8 */
 }