On the revprop-caching-ng branch:  Make the atomic revprop change API
work even in the case of stale caches.

When writing revprops, always read the original from disk instead of
from cache.

* subversion/libsvn_fs_fs/revprops.h
  (svn_fs_fs__get_revision_proplist): Add BYPASS_CACHE option.

* subversion/libsvn_fs_fs/revprops.c
  (svn_fs_fs__get_revision_proplist): Skip cache lookup when the
                                      bypass option is set.

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_fs_fs__revision_prop): r/o access may use the cache.
  (change_rev_prop_body): r/w access shall bypass them.

* subversion/libsvn_fs_fs/fs.c
  (fs_revision_proplist): New simple signature adapter.
  (fs_vtable): Call the adapter as it has the correct signature.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/revprop-caching-ng@1619862 13f79535-47bb-0310-9956-ffa450edef68