Remove extra colon from /wd compiler directive.

On conversion the VS2005 reports:
ommand line error D8021 : invalid numeric argument '/wd:4996'	cl

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@464209 13f79535-47bb-0310-9956-ffa450edef68