This change reduces the length of the kernel version that is set by the
build process. We find that the most recent version is too long for the
kernel and causes certain kernel detection processes to fail.
We also remove the concept of build flavor or build profile. These
concepts should be reflected in the Debian package name and version
instead of separately in the kernel version.
This change removes the kernel release from the full kernel version.
This is used by Proxmox to identify differences in the kernel ABI.
However, since this project does not track these changes, we remove the
kernel release number altogether.
This change updates the build code to support in-tree builds. This is
easier to manage for CI builds and reduces the amount of IO operations
necessary for the build process.
