r8515: ldb_dn_cmp now uses ldb_dn_compare so that the DNs are compared

r8515: ldb_dn_cmp now uses ldb_dn_compare so that the DNs are compared
on a content level not ona form level, his means that the 2 DNs:
a) cn= user, dc=this, dc = is,dc=test
b) cn=user,dc=this,dc=is,dc=test
are now identical even if the string form differ (spaces)
(This used to be commit 76d496c30867ae80434483a34b0d842523aed762)