This is necessary to build against kernel version 3.19 since commit
(78d28e651f97866d608d9b41 "kill f_dentry macro") [1]
[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=78d28e651
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
(cherry picked from commit 4d86a8f3f6)