Increase timeout of nss/tst-nss-files-hosts-multi

Increase timeout from the default 20s to 40s. This test makes close to
2 million syscalls with distribution:

1180249 connect
 297952 getsockname
 144040 lseek
 143734 read
  14466 close
...

connect can be slow, so the default timeout was not enough on slow
systems.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	* nss/tst-nss-files-hosts-multi.c (TIMEOUT): Define.