Create a "backport" branch for supporting Neon 0.30.x in 1.7.x.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x-neon-0.30@1566319 13f79535-47bb-0310-9956-ffa450edef68
* configure.ac: Allow building with Neon 0.30.x.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x-neon-0.30@1566320 13f79535-47bb-0310-9956-ffa450edef68
Merge the 1.7.x-neon-0.30 branch:

 * r1566320
   Allow building with Neon 0.30.x.
   Justification:
     Version 0.30.0 is the latest Neon release, and the only reason that
     we cannot use it in 1.7.x is the restriction in configure.ac.
   Branch:
     ^/subversion/branches/1.7.x-neon-0.30
   Votes:
     +1: brane, breser, rhuijben


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x@1568588 13f79535-47bb-0310-9956-ffa450edef68