MDEV-22456 post-fix: Remove unused variable

Author: dr-m

storage/innobase/fsp/fsp0fsp.cc

@@ -3170,10 +3170,7 @@ fseg_free_extent(
 ut_ad(mach_read_from_4(seg_inode + FSEG_MAGIC_N)
  == FSEG_MAGIC_N_VALUE);
 ut_d(space->modify_check(*mtr));
-
-#if defined BTR_CUR_HASH_ADAPT || defined UNIV_DEBUG
-const ulint first_page_in_extent = page - (page % FSP_EXTENT_SIZE);
-#endif /* BTR_CUR_HASH_ADAPT || UNIV_DEBUG */
+ut_d(ulint first_page_in_extent = page - (page % FSP_EXTENT_SIZE));
 
 if (xdes_is_full(descr, mtr)) {
 flst_remove(seg_inode + FSEG_FULL,