Avoid abort() call in the enforce_consistent_revprop_caching() test on Visual
Studio X86 <= 2012 by registering an fs warning func. This should make the
Windows buildbots green again.

* subversion/tests/libsvn_fs_fs/fs-fs-pack-test.c
  (enforce_consistent_revprop_caching): Set warning funcs on two opened fss.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1619737 13f79535-47bb-0310-9956-ffa450edef68