InnoDB: fix a compilation error due to missing typedef (Bug #7383)

rem0rec.ic:
  Replace (int16_t) with (signed short).


innobase/include/rem0rec.ic:
  Replace (int16_t) with (signed short).

innobase/include/rem0rec.ic

@@ -257,7 +257,7 @@ rec_get_next_offs(
 	ibool	comp)	/* in: TRUE=compact page format */
 {	
 	if (comp) {
-		lint ret = (int16_t) rec_get_bit_field_2(rec, REC_NEXT,
+		lint ret = (signed short) rec_get_bit_field_2(rec, REC_NEXT,
 						REC_NEXT_MASK, REC_NEXT_SHIFT);
 #if UNIV_PAGE_SIZE <= 32768
 		/* with 64 KiB page size, the pointer will "wrap around",