s3/lib: add option "serverid watch:debug = yes" to print kernel stack of hanging...

s3/lib: add option "serverid watch:debug = yes" to print kernel stack of hanging process

We only do if sys_have_proc_fds() returns true, so it's most likely
linux...

Enabled by default with log level 10...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15624

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Ralph Boehme <slow@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>