On RHEL8 kmodtool and kernel_module_package_buildreqs are not installed with kernel-devel.

kernel_module_package_buildreqs is defined in kernel-rpm-marcos.

If kernel-rpm-macros is not installed, the Lustre RPM build will report:

Dependency tokens must begin with alpha-numeric, '_' or '/': BuildRequires: %kernel_module_package_buildreqs

We should patch the lustre.spec.in to help the developer understanding the detailed information for the required package when kernel-rpm-macros is not installed.