xrootd: Upgrade to xrootd4j 1.2.2

Fixes compatibility issues with xrootd plugins.

Target: trunk
Request: 2.7
Request: 2.6
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6233