mds: adjust flock lock state on export

Looks like this was missed when flocklock was added.  Did a quick grep and
it doesn't look like it is missing anywhere else.

Signed-off-by: Sage Weil <sage@newdream.net>

src/mds/Migrator.cc

@@ -1075,6 +1075,7 @@ void Migrator::finish_export_inode(CInode *in, utime_t now, list<Context*>& fini
   in->nestlock.export_twiddle();
   in->xattrlock.export_twiddle();
   in->snaplock.export_twiddle();
+  in->flocklock.export_twiddle();
   in->policylock.export_twiddle();
   
   // mark auth