branches/zip: Fix a bug that was introduced in r2123.

buf_block_is_uncompressed(): Check that the pointer is aligned.  Use the
C modulus operator % instead of ut_align_offset(), because sizeof(buf_block_t)
is not guaranteed to be a power of 2.

buf/buf0buf.c

@@ -1671,7 +1671,7 @@ buf_block_is_uncompressed(
 
 	ut_ad(mutex_own(&buf_pool->mutex));
 
-	if (UNIV_UNLIKELY(ut_align_offset(block, sizeof *block) != 0)) {
+	if (UNIV_UNLIKELY((((ulint) block) % sizeof *block) != 0)) {
 		/* The pointer should be aligned. */
 		return(FALSE);
 	}