wldap32: Return an error when ldap_parse_sort_control or ldap_parse_vlv_control is called with NULL control array.

Rename variables to help the reader following the xml traversal. While doing
that, I encountered a possible typo, as node_list2 was never used after being
acquired. This version now really tries to delete a grandchild and expects
a failure.

x11drv: ime: In the update functions if we get a null string with a len report this and fix len to be 0 (Coverity 656 and 655).

Fixes winmm:wave test hanging.

Fixes failing dsound tests in wine.