installkernel.ebuild: re-add lost S=

Signed-off-by: Nowa Ammerlaan <nowa@gentoo.org>

Author: Nowa-Ammerlaan

installkernel-9999.ebuild

@@ -16,6 +16,7 @@ if [[ ${PV} == 9999 ]]; then
 	EGIT_REPO_URI="https://github.com/projg2/installkernel-gentoo.git"
 else
 	SRC_URI="https://github.com/projg2/installkernel-gentoo/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+	S="${WORKDIR}/${PN}-gentoo-${PV}"
 	KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~loong ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~amd64-linux ~x86-linux"
 fi