(ITS#4128) back-config core dumps when initializing directory

[ando@sys-net.it]

Full_Name: Pierangelo Masarati
Version: HEAD
OS: irrelevant
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (81.74.43.82)
Submitted by: ando


When initializing back-config (either with slapd or slaptest) for an existing
directory, i.e. launching the tool/daemon with both -f and -F, slapd core dumps
because slap_queue_csn() tries to lock/unlock a NULL op->o_bd->be_pcl_mutexp
pointer.  I think the "right" solution is to not request CSN management within
back-ldif when calling slap_add_opattrs() if op->o_bd->be_pcl_mutexp is NULL. 
I'm committing a fix in this sense; please review.

p.