FSAL_GLUSTER: Fixes for pynfs failures and FSAL lock_op
implemetation.

FSAL mknod was not handling nodetype, causing all special files
to be created as regular files.
Post unlink of pinned files (fd open), caused failure on getattr,
instead of using the fd to get the required attributes.
lock_op not implemented caused failures in various lock tests by
pynfs, this is now fixed.