pgrowlocks: Fix incorrect format placeholders

Transaction IDs should be printed as unsigned, similar to xidout().

contrib/pgrowlocks/pgrowlocks.c

@@ -168,7 +168,7 @@ pgrowlocks(PG_FUNCTION_ARGS)
 															 PointerGetDatum(&tuple->t_self));
 
 			values[Atnum_xmax] = palloc(NCHARS * sizeof(char));
-			snprintf(values[Atnum_xmax], NCHARS, "%d", xmax);
+			snprintf(values[Atnum_xmax], NCHARS, "%u", xmax);
 			if (infomask & HEAP_XMAX_IS_MULTI)
 			{
 				MultiXactMember *members;
@@ -209,7 +209,7 @@ pgrowlocks(PG_FUNCTION_ARGS)
 							strcat(values[Atnum_modes], ",");
 							strcat(values[Atnum_pids], ",");
 						}
-						snprintf(buf, NCHARS, "%d", members[j].xid);
+						snprintf(buf, NCHARS, "%u", members[j].xid);
 						strcat(values[Atnum_xids], buf);
 						switch (members[j].status)
 						{
@@ -250,7 +250,7 @@ pgrowlocks(PG_FUNCTION_ARGS)
 				values[Atnum_ismulti] = pstrdup("false");
 
 				values[Atnum_xids] = palloc(NCHARS * sizeof(char));
-				snprintf(values[Atnum_xids], NCHARS, "{%d}", xmax);
+				snprintf(values[Atnum_xids], NCHARS, "{%u}", xmax);
 
 				values[Atnum_modes] = palloc(NCHARS);
 				if (infomask & HEAP_XMAX_LOCK_ONLY)