package_rpm: Ensure we take the sstate shared lockfile in the place we write files
The point we need to take the lock is when the rpm files are written into the
deploy rpm directory. Since sstate makes the actual installation of the files,
that is the point we need to take the lock. This also stops the deploy/rpm
directory being accessed for a lock before it exists.
[YOCTO #797]
[YOCTO #925]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
