Revert ticket #1893 - netbsd-5 does not have pathbuf_destroy()
Revert ticket 1893.
Apply patch, requested by bad in ticket #1887:
	lib/libc/net/gethnamaddr.c			1.79-1.82 via patch
	lib/libc/net/getnameinfo.3			1.37-1.40 via patch
	lib/libc/net/getnameinfo.c			1.4 via patch
	lib/libc/net/hostent.h				1.1, 1.2 via patch
	lib/libc/net/sethostent.c			1.17-1.19 via patch

Make getnameinfo(3) re-entrant (ahem __ypdomain).
Add not advertised reentrant functions: {get,set,end}hostent_r,
gethostbyname{,2}_r, gethostbyaddr_r. Make getnameinfo(3) use
gethostbyaddr_r(3).
Implement no-check-names.
Ticket 1887