fuse: add mtab entry asynchronously
fuse: add mtab entry asynchronously

Instead of taking libfuse's approach to the bug referred
-- making use of an ad-hoc mount option --, we get over
the issue by not waiting for mtab manipulation to complete.
If mtab manipulation happens to fail for some reason, just
log an error message (instead of aborting the mount).

Signed-off-by: Csaba Henk <csaba@gluster.com>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 511 (mount hangs with some audit configurations)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=511

Kaushikbv/Gluster,Kaushikbv/Gluster,Kaushikbv/Gluster