r13328: After the attribute name check cleanup it turned up ldb_caseless_cmp()

r13328: After the attribute name check cleanup it turned up ldb_caseless_cmp()
was used just in one places and by mistake, as there we should have
been using ldb_attr_cmp()

Remove ldb_caseless_cmp() ... going on with the cleanup and utf8 compliance
effort.

Simo.
(This used to be commit afda68d7bf655a9145648856d29e6e64b9f21aa3)