Sync FSX with FSFS:  Record-only merge r1597414, r1598273, r1599140,
r1607085, r1612407, r1613339, r1618226, r1619068, r1624265, r1627948,
r1628083, r1628158, r1628676 and r1632646 from libsvn_fs_fs.

These revisions have already updated both backends.

* subversion/libsvn_fs_x
  (): Update mergeinfo.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1634940 13f79535-47bb-0310-9956-ffa450edef68