* w32/npth.c (npth_create): Examine ->detachstate directly when
USER_ATTR != NULL.  Remove allocation of ATTR.
(npth_rwlock_init): Examine ->kind directly when USER_ATTR != NULL.
Remove allocation of ATTR.
(npth_clock_gettime): Remove unused USECS variable.
(calculate_timeout, npth_tryjoin_np): Remove unused RES variable.
(npth_join, onpth_mutex_trylock): Likewise.
(npth_cond_broadcast): Remove unused ANY variable.
(rwlock_init_check): It's not used, so, if-out by preprocessor.
(npth_eselect): Remove unused sock_event_idx variable.