Subtracted 1 from size argument in some calls to strncpy(3).

Subtracted 1 from size argument in some calls to strncpy(3).

This fixed "specified bound [n] equals destination size" warnings
found by gcc -Wstringop-truncation.

Also, fixed harmless copy-and-paste error (sizeof(tmpfil) instead
of sizeof(drft) in uip/rcvdist.c) introduced in commit 2f689a1cb.