Install usign to OpenWRT-skel

opkg-feed/installer/openwrt-sdxlemur-skel/usr/bin/signify

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+usign

opkg-feed/installer/openwrt-sdxlemur-skel/usr/lib/opkg/info/usign.control

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+Package: usign
+Version: 2020-05-23-f1f65026-1
+Depends: libc, libubox20220515
+Source: package/system/usign
+SourceName: usign
+License: ISC
+Section: base
+SourceDateEpoch: 1679485838
+Maintainer: Felix Fietkau <nbd@nbd.name>
+Architecture: arm_cortex-a7_neon-vfpv4
+Installed-Size: 14348
+Description:  OpenWrt signature verification utility

opkg-feed/installer/openwrt-sdxlemur-skel/usr/lib/opkg/info/usign.list

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+/usr/bin/usign
+/usr/bin/signify

opkg-feed/installer/openwrt-sdxlemur-skel/usr/lib/opkg/info/usign.prerm

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+#!/bin/sh
+[ -s ${IPKG_INSTROOT}/lib/functions.sh ] || exit 0
+. ${IPKG_INSTROOT}/lib/functions.sh
+default_prerm $0 $@