tcpwrappers: Use xlog() instead of perror(3) and syslog(2)

Clean up: Replace calls to syslog(2) and perror(3) in from_local.c
with calls to xlog().  The problems displayed by the perror(3) calls
especially should be reported.  Currently they are never seen in the
system log.

As part of a build test, I defined TEST, and found a couple of
problems with main(), which are also addressed in this patch.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>