kbuild: deb-pkg: do not include empty hook directories

The linux-image package currently includes empty hook directories
(/etc/kernel/{pre,post}{inst,rm}.d/ by default).

These directories were perhaps intended as a fail-safe in case no
hook scripts exist there.

However, they are really unnecessary because the run-parts command is
already guarded by the following check:

    test -d ${debhookdir}/${script}.d && run-parts ...

The only difference is that the run-parts command either runs for empty
directories (resulting in a no-op) or is skipped entirely.

The maintainer scripts will succeed without these dummy directories.

The linux-image packages from the Debian kernel do not contain
/etc/kernel/*.d/, either.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/package/builddeb

@@ -76,8 +76,6 @@ install_maint_scripts () {
 	# so do we; recent versions of dracut and initramfs-tools will obey this.
 	debhookdir=${KDEB_HOOKDIR:-/etc/kernel}
 	for script in postinst postrm preinst prerm; do
-		mkdir -p "${pdir}${debhookdir}/${script}.d"
-
 		mkdir -p "${pdir}/DEBIAN"
 		cat <<-EOF > "${pdir}/DEBIAN/${script}"
 		#!/bin/sh