eclass/eapi9-ver: Add from Gentoo

It's from Gentoo commit 65cb33ec019e2ce8980f546a137ba27c55042c55.

sdk_container/src/third_party/portage-stable/eclass/eapi9-ver.eclass

@@ -0,0 +1,50 @@
+# Copyright 2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: eapi9-ver.eclass
+# @MAINTAINER:
+# Ulrich Müller <ulm@gentoo.org>
+# @AUTHOR:
+# Ulrich Müller <ulm@gentoo.org>
+# @SUPPORTED_EAPIS: 7 8
+# @BLURB: Testing implementation of EAPI 9 ver_replacing
+# @DESCRIPTION:
+# A stand-alone implementation of the ver_replacing function aimed
+# for EAPI 9.  Intended to be used for wider testing of the proposed
+# function and to allow ebuilds to switch to the new model early, with
+# minimal change needed for the actual EAPI 9.
+#
+# @CODE
+# if ver_replacing -lt 1.2; then
+#     elog "The frobnicate command was dropped in version 1.2"
+# fi
+# @CODE
+
+case ${EAPI} in
+	7|8) ;;
+	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
+esac
+
+# @FUNCTION: ver_replacing
+# @USAGE: <op> <ver>
+# @RETURN: 0 if any element of REPLACING_VERSIONS qualifies, 1 otherwise
+# @DESCRIPTION:
+# Compare each element <v> of REPLACING_VERSIONS with version <ver>
+# using ver_test().  Return 0 (true) if any element <v> fulfills
+# "ver_test <v> <op> <ver>", 1 (false) otherwise.
+#
+# Note: If REPLACING_VERSIONS is empty, 1 (false) is returned.
+ver_replacing() {
+	case ${EBUILD_PHASE} in
+		pretend|setup|preinst|postinst) ;;
+		*) die "ver_replacing is meaningless in the ${EBUILD_PHASE} phase" ;;
+	esac
+
+	[[ $# -eq 2 ]] || die "Usage: ver_replacing <op> <ver>"
+
+	local v
+	for v in ${REPLACING_VERSIONS}; do
+		ver_test "${v}" "$@" && return 0
+	done
+	return 1
+}