Convert ETXTBSY to ERR_FSAL_SHARE_DENIED instead of FSAL_FILE_OPEN.
For v4 it will be converted to NFS4ERR_SHARE_DENIED.
For v3 it will be converted to NFS3ER_JUKEBOX, which will allow a client to wait
for the share reservation to be released.

Signed-off-by: Srikrishan Malik <srimalik@in.ibm.com>