move rc_svcdir to /run/openrc on Linux systems

If you are not using linux, this should not affect you.

If you are using linux, from this point forward, openrc requires the
/run directory to be a mounted tmpfs. If it is, you can run
@LIBEXECDIR@/sh/migrate-to-run.sh as root to migrate your dependency
tree and state information to the new location. If it is not, you must
create the /run directory as root with permissions 755 then reboot your
system.

reported-by: Maxim Kammerer <mk@dee.su>
X-Gentoo-Bug: 401059
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=401059

sh/Makefile

@@ -12,8 +12,10 @@ include ${MK}/os.mk
 SRCS-FreeBSD=
 BIN-FreeBSD=
 
-SRCS-Linux=	cgroup-release-agent.sh.in init-early.sh.in udhcpc-hook.sh.in
-BIN-Linux=	cgroup-release-agent.sh init-early.sh udhcpc-hook.sh
+SRCS-Linux=	cgroup-release-agent.sh.in init-early.sh.in migrate-to-run.sh.in \
+	udhcpc-hook.sh.in
+BIN-Linux=	cgroup-release-agent.sh init-early.sh migrate-to-run.sh \
+	udhcpc-hook.sh
 
 SRCS-NetBSD=	ifwatchd-carrier.sh.in ifwatchd-nocarrier.sh.in
 BIN-NetBSD=	ifwatchd-carrier.sh ifwatchd-nocarrier.sh