Add cleanup scripts for future imports.

external/bsd/libc++/prepare-import.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+# $NetBSD: prepare-import.sh,v 1.1 2013/05/17 23:00:22 joerg Exp $
+#
+# Checkout libc++ and libcxxrt in the corresponding subdirectories of
+# dist.  Run this script and check for additional files and
+# directories to prune, only relevant content should be included.
+
+set -e
+
+cd dist/libcxx
+rm -rf .svn cmake Makefile CMakeLists.txt lib src/support www .arcconfig
+rm -rf include/support
+cd ../libcxxrt
+rm -rf .git CMakeLists.txt */CMakeLists.txt src/doxygen_config
+