pick this up from 2.1-dev:

mod_dav: Fix a problem that could cause crashes when manipulating
locks on some platforms.

Reviewed by:	jorton, nd


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@103526 13f79535-47bb-0310-9956-ffa450edef68