hhvm on beta: remove /etc/init.d/hhvm; simplify libmemcached check

- Remove /etc/init.d/hhvm in addition to /etc/init.d/hhvm-fastcgi
- Avoid having a gigantic gross command-line in the check for the
  libmemcached10 patch exec.

Change-Id: I9236c995ce7fda383bc33e4e0d64a7be1b33c52e
Merge "hhvm on beta: remove /etc/init.d/hhvm; simplify libmemcached check" into production