sys-fs/mdadm: Sync with Gentoo

It's from Gentoo commit 88363d5349960e09082915da4e7e5b08e379c564.

Signed-off-by: Flatcar Buildbot <buildbot@flatcar-linux.org>

sdk_container/src/third_party/portage-stable/sys-fs/mdadm/files/mdraid.rc

@@ -7,11 +7,24 @@ depend() {
 	after modules
 }
 
+assemble() {
+	local rv
+	mdadm -As ${MDADM_ASSEMBLE_OPTS} 2>&1
+	rv=$?
+	if [ ${rv} -eq 2 ]; then
+		# mdadm exits with status 2 when there is nothing to assemble.
+		# This is undocumented.
+		# https://bugs.gentoo.org/295397
+		return 0
+	fi
+	return "${rv}"
+}
+
 start() {
 	local output
 
 	ebegin "Starting up RAID devices"
-	output=$(mdadm -As ${MDADM_ASSEMBLE_OPTS} 2>&1)
+	output=$(assemble)
 	eend $? "${output}"
 
 	local pat="/dev/md_d*"

sdk_container/src/third_party/portage-stable/sys-fs/mdadm/mdadm-4.4-r1.ebuild

@@ -1,4 +1,4 @@
-# Copyright 1999-2025 Gentoo Authors
+# Copyright 1999-2026 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8