speed-up md5 by avoiding some memcopies
    
PR: 49011
Submitted by: Stefan Fritsch, Stefan Fuhrmann <stefanfuhrmann alice-dsl de>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1460244 13f79535-47bb-0310-9956-ffa450edef68