pg_upgrade: fix parallel/-j crash on Windows

This fixes the problem of passing the wrong function pointer when doing
parallel copy/link operations on Windows.
Backpatched to 9.3beta.
Found and patch supplied by Andrew Dunstan

contrib/pg_upgrade/parallel.c

@@ -244,7 +244,7 @@ parallel_transfer_all_new_dbs(DbInfoArr *old_db_arr, DbInfoArr *new_db_arr,
 		strcpy(new_arg->new_pgdata, new_pgdata);
 		strcpy(new_arg->old_tablespace, old_tablespace);
 
-		child = (HANDLE) _beginthreadex(NULL, 0, (void *) win32_exec_prog,
+		child = (HANDLE) _beginthreadex(NULL, 0, (void *) win32_transfer_all_new_dbs,
 										new_arg, 0, NULL);
 		if (child == 0)
 			pg_log(PG_FATAL, "could not create worker thread: %s\n", strerror(errno));