Merge r1514763 from trunk:

 * r1514763
   ra_serf: Use case-insensitive hostname comparision when validating server
   certificate as it specified in RFC 2459.
   Justification:
     SSL certificate with uppercase letters in hostname considered as
     untrusted. Regression from Subversion 1.7.x.
   Votes:
     +1: ivan, rhuijben, stefan2


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1515070 13f79535-47bb-0310-9956-ffa450edef68