spec: Add vmlinux.h to kernel-devel package

Adding/generating vmlinux.h by bpftool to the kernel-devel package:

$ rpm -ql -p kernel-devel-5.13.0-0.rc...x86_64.rpm | grep vmlinux.h /usr/src/kernels/5.13.0-0.rc...x86_64/vmlinux.h

Some tools like bpftool or selftest need vmlinux.h to properly compile. The vmlinux.h will be used by build system to compile tools separately.

Signed-off-by: Jiri Olsa jolsa@redhat.com