update Uninstaller A/B mount code

uninstaller/META-INF/com/google/android/update-binary

@@ -138,7 +138,8 @@ mount_partitions () {
 
 	is_mounted /data || mount /data || error "failed to mount /data!"
 
-	! is_mounted /system && mount -o rw /system
+	mount -o bind /dev/urandom /dev/random
+	! is_mounted /system && mount -o rw /system || mount -o rw,remount /system
 
 	if [ ! -f /system/build.prop ]; then
 		SYSTEMBLOCK=$(find /dev/block -iname system${SLOT} | head -n 1)
@@ -155,6 +156,18 @@ mount_partitions () {
 
 	[ ! -f /system/build.prop ] && error "failed to mount /system (unsupported A/B device?)"
 
+	if [ -L /system/vendor ]; then
+		! is_mounted /vendor && mount /vendor
+		if ! is_mounted /vendor; then
+			VENDORBLOCK=$(find /dev/block -iname vendor${SLOT} | head -n 1)
+			mount -t ext4 -o ro ${VENDORBLOCK} /vendor
+		fi
+	elif [ -d /system/vendor ]; then
+		### XXX work-around required for some ROMs
+		echo " xxx compat /vendor link created!"
+		ln -sf /system/vendor /vendor >/dev/null
+	fi
+
 	if [ ! -d /system/xbin ]; then
 		NANODROID_BINDIR=/system/bin
 	else	NANODROID_BINDIR=/system/xbin