This script is used in the non-dkms scst package. The purpose of package
is to determine kernel location at compile-time, as opposed to the
package installation time. However, calling `uname -r` in package
installation time violates that idea because it would get some random
kernel that was running on the machine. This problem is particularly
seen in containers, because in those `uname` shows the kernel running on
the host, rather than the one running inside container.
Fix this by determining the kernel location in `preinst` script at
compile time as well.
