ovs-vswitchd: Call mlockall() from the daemon, not the parent or monitor.

ovs-vswitchd: Call mlockall() from the daemon, not the parent or monitor.

mlockall(2) says:

       Memory  locks  are not inherited by a child created via fork(2) and are
       automatically removed  (unlocked)  during  an  execve(2)  or  when  the
       process terminates.

which means that --mlockall was ineffective in combination with --detach
or --monitor or both.  Both are used in the most common production
configuration of Open vSwitch, so this means that --mlockall has never been
effective in production.

Signed-off-by: Ben Pfaff <blp@nicira.com>