busybox add initramfs hook

sys/base/busybox/files/busybox.sysconf

@@ -0,0 +1,8 @@
+#!/bin/busybox ash
+/bin/busybox mkdir -p /var/lib/ymp/sysconf/busybox/
+if /bin/busybox [ ! -f /var/lib/ymp/sysconf/busybox/postinstall.done ] ; then
+    /bin/busybox --install -s /bin
+    /bin/busybox install /bin/busybox /bin/su
+    /bin/busybox chmod u+s /bin/su
+    /bin/busybox date > /var/lib/ymp/sysconf/busybox/postinstall.done
+fi