nfsd: make NFSv4 grace time per net

Grace time is a part of NFSv4 state engine, which is constructed per network
namespace.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfsd.h

@@ -276,8 +276,6 @@ extern struct timeval	nfssvc_boot;
 
 #ifdef CONFIG_NFSD_V4
 
-extern time_t nfsd4_grace;
-
 /* before processing a COMPOUND operation, we have to check that there
  * is enough space in the buffer for XDR encode to succeed.  otherwise,
  * we might process an operation with side effects, and be unable to