release: Allow empty extra distributions.

For example, WITHOUT_SHAREDOCS= in src.conf creates an empty doc
distribution.

Submitted by:	Kurt Lidl
Tested by:	Kurt Lidl
Discussed with:	gjb
MFC after:	1 week
Add a "-v" (verbose) option to the gssd daemon, to help
with diagnosis of kerberized NFS mount problems. When set,
messages are sent to syslog() (or fprintf(stderr,...) if
"-d" is also specified) to indicate activity/results of
kgssapi upcalls.

Reviewed by:	jhb
MFC after:	2 weeks