testparm: do not fail if /run/samba does not exist

testparm: do not fail if /run/samba does not exist

testparm explicitly fails if $piddir or $lockdir does not exist.
However, the daemons which actually use these directories, will
create it on demand, there is no need to fail even simple testparm
operations if the dirs are not there.

This change lets to (pre)configure samba without bothering to
pre-create the directories which are overwise needed only to fulfil
testparm criteria.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Gbp-Pq: Name testparm-do-not-fail-if-pid-dir-does-not-exist.patch