Fix the Windows non-debug build

warning C4390:  ';': empty controlled statement found; is this the intent?

storage/innobase/include/trx0sys.h

@@ -72,8 +72,7 @@ inline buf_block_t *trx_sysf_get(mtr_t* mtr, bool rw= true)
 {
   buf_block_t* block = buf_page_get(page_id_t(TRX_SYS_SPACE, TRX_SYS_PAGE_NO),
 				    0, rw ? RW_X_LATCH : RW_S_LATCH, mtr);
-  if (block)
-    buf_block_dbg_add_level(block, SYNC_TRX_SYS_HEADER);
+  ut_d(if (block) buf_block_dbg_add_level(block, SYNC_TRX_SYS_HEADER);)
   return block;
 }