Draft: kernel.spec: add automotive as a kernel variant

This change promotes the automotive kernel to an official variant,
allowing it to be built alongside the stock kernel.

The automotive kernel can be built in two ways: a separate build for the
independent kernel-automotive package and as a variant of the kernel
package.

To build the kernel-automotive package in CBS or brew:

make AUTOMOTIVE_BUILD=1 dist-brew
make AUTOMOTIVE_BUILD=1 dist-cbs

This defines the name of the automotive kernel built as a variant of the
kernel package to kernel-ivos.

To build the kernel package in koji or brew:

make DISTRO=rhel DIST=.eln dist-koji
make DISTRO=centos dist-brew

The name change to "ivos" is required because for a rawhide or ELN rcX
build it can be easy to exceed the 64 character limit of UTS_RELEASE
if we were to use "automotive" in the kernel version. Now, the much
shorter "ivos" (In-Vehicle Operating System) will be used.

The Makefile, configs and the spec file will continue to use the term
"automotive" to describe both the kernel-automotive package and the
kernel-ivos variant.

Signed-off-by: Scott Weaver scweaver@redhat.com