modules: Fix some compiler warnings.

trunk patch: http://svn.apache.org/r1500345
             http://svn.apache.org/r1500362
             http://svn.apache.org/r1500423
             http://svn.apache.org/r1500483
             http://svn.apache.org/r1500519

Submitted by: fuankg
Reviewed by: jim, minfrin


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1523259 13f79535-47bb-0310-9956-ffa450edef68