xsfbs: add a repack script for uscan

This will automatically prune upstream tarballs

debian/xsfbs/repack.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+set -e
+
+if ! [ -d debian/prune ]; then
+	exit 0
+fi
+
+if [ "x$1" != x--upstream-version ]; then
+	exit 1
+fi
+
+version="$2"
+filename="$3"
+
+if [ -z "$version" ] || ! [ -f "$filename" ]; then
+	exit 1
+fi
+
+dir="$(pwd)"
+tempdir="$(mktemp -d)"
+
+cd "$tempdir"
+tar xf "$dir/$filename"
+cat "$dir"/debian/prune/* | while read file; do rm -f */$file; done
+
+tar czf "$dir/$filename" *
+cd "$dir"
+rm -rf "$tempdir"
+echo "Done pruning upstream tarball"
+
+exit 0