Added hacky fetchsvn component which allows users to fetch code over svn+ssh

svn path=/nixpkgs/trunk/; revision=11455

pkgs/build-support/fetchsvnssh/builder.sh

@@ -0,0 +1,15 @@
+source $stdenv/setup
+
+header "exporting $url (r$rev) into $out"
+
+if test "$sshSupport"; then
+    export SVN_SSH="$openssh/bin/ssh"
+fi
+
+# Pipe the "p" character into Subversion to force it to accept the
+# server's certificate.  This is perfectly safe: we don't care
+# whether the server is being spoofed --- only the cryptographic
+# hash of the output matters.
+expect -f $sshSubversion "$username" "$password" "$rev" "$url" $out
+
+stopNest