redhat: pass correct RPM_VMLINUX_H to bpftool install

RPM doesn't carry over variables between %build and %install, so we end up using bpftool_make with empty RPM_VMLINUX_H.

Link: infrastructure#340 Link: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=e7b64f9d3f5b10186038201e0b91f734cbd7fc3d Signed-off-by: Jan Stancek jstancek@redhat.com