Bug#59585 Fix 58912 introduces compiler warning

due to potentially uninitialized variable

row_upd_changes_ord_field_binary(): Initialize dfield_len to suppress the
warning. The compiler cannot know that row_ext_lookup() does initialize
dfield_len for us, as it is defined in a different module.

storage/innodb_plugin/ChangeLog

+2011-01-25	The InnoDB Team
+
+	* row/row0upd.c:
+	Bug#59585 Fix 58912 introduces compiler warning
+	due to potentially uninitialized variable
+
 2011-01-25	The InnoDB Team
 
 	* mtr/mtr0log.c:

storage/innodb_plugin/row/row0upd.c

@@ -1252,6 +1252,10 @@ row_upd_changes_ord_field_binary(
 		    || dfield_is_null(dfield)) {
 			/* do nothing special */
 		} else if (UNIV_LIKELY_NULL(ext)) {
+			/* Silence a compiler warning without
+			silencing a Valgrind error. */
+			dfield_len = 0;
+			UNIV_MEM_INVALID(&dfield_len, sizeof dfield_len);
 			/* See if the column is stored externally. */
 			buf = row_ext_lookup(ext, col_no, &dfield_len);