Installation of linux_base-7.1_2 fails when linprocfs is
mounted. Unmounting linprocfs before installing works
around the issue.
At Lars' suggestion, this script also mounts the linprocfs after
installation. I assume that if the user has a linprocfs entry in
/etc/fstab, the user wants it to be mounted. It also seemed like
a good idea to un-mount it before de-installation.
PR: 46172
script so that the behaviour of a package installation matches
that of a port installation identically.
Note that, in the package case, we already have a valid run-time
linker hints file for Linux.