virtual/service-manager: add USE=system-init for s6-rc & runit

otherwise, it's not a provider of virtual/service-manager

Bug: https://bugs.gentoo.org/375115
Signed-off-by: Z. Liu <zhixu.liu@gmail.com>
Part-of: https://github.com/gentoo/gentoo/pull/44909
Closes: https://github.com/gentoo/gentoo/pull/44909
Signed-off-by: Sam James <sam@gentoo.org>

virtual/service-manager/service-manager-2-r1.ebuild

@@ -0,0 +1,24 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DESCRIPTION="Virtual for various service managers"
+
+SLOT="0"
+KEYWORDS="~alpha amd64 arm arm64 ~hppa ~loong ~m68k ~mips ppc ppc64 ~riscv ~s390 ~sparc x86 ~arm64-macos ~x64-macos ~x64-solaris"
+IUSE="systemd"
+
+RDEPEND="
+	!prefix-guest? (
+		systemd? ( sys-apps/systemd )
+		!systemd? ( || (
+				sys-apps/openrc
+				kernel_linux? ( || (
+					sys-apps/s6-rc[system-init(-)]
+					sys-process/runit[system-init(-)]
+				) )
+			)
+		)
+	)
+"