branches/zip: ibuf_index_page_calc_free(): Add const qualifiers.

include/ibuf0ibuf.ic

@@ -198,10 +198,10 @@ UNIV_INLINE
 ulint
 ibuf_index_page_calc_free(
 /*======================*/
-				/* out: value for ibuf bitmap bits */
-	ulint		zip_size,/* in: compressed page size in bytes;
-				0 for uncompressed pages */
-	buf_block_t*	block)	/* in: buffer block */
+					/* out: value for ibuf bitmap bits */
+	ulint			zip_size,/* in: compressed page size in bytes;
+					0 for uncompressed pages */
+	const buf_block_t*	block)	/* in: buffer block */
 {
 	ulint	max_ins_size;
 
@@ -213,9 +213,12 @@ ibuf_index_page_calc_free(
 	if (!zip_size) {
 		return(ibuf_index_page_calc_free_bits(0, max_ins_size));
 	} else {
-		page_zip_des_t*	page_zip = buf_block_get_page_zip(block);
-		lint		zip_max_ins = page_zip_max_ins_size(
-			page_zip, FALSE/* not clustered */);
+		const page_zip_des_t*	page_zip;
+		lint			zip_max_ins;
+
+		page_zip = buf_block_get_page_zip(block);
+		zip_max_ins = page_zip_max_ins_size(page_zip,
+						    FALSE/* not clustered */);
 
 		if (UNIV_UNLIKELY(zip_max_ins < 0)) {
 			max_ins_size = 0;