libs: update to bugfix nfs4j-0.7.3

Changelog for nfs4j-0.7.2..nfs4j-0.7.3
    * [f2b0d2b] vfs: fix regression introduced in 1c916c5

Acked-by: Gerd Behrmann
Target: master, 2.8, 2.7
Require-book: no
Require-notes: no
(cherry picked from commit 2d14212ba231232090277b767b7e3352d60474d1)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Merge pull request #406 from kofemann/nfs-0.7.3-2.8

libs: update to bugfix nfs4j-0.7.3