Discard error from aclocal call (which seems to be needed on some Mac…

… installations)

We do this aclocal call because it seems to be needed on some Mac
installations to enable autoreconf to run. But if the paths don't exist
we get an error. So just discard the error.

autogen.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env sh
 which autoreconf > /dev/null || (echo "Please install autoconf" && exit 1)
 # on OSX autoconf may need a little help with these paths
-aclocal -I /opt/local/share/aclocal -I /usr/local/share/aclocal
+aclocal -I /opt/local/share/aclocal -I /usr/local/share/aclocal 2> /dev/null
 autoreconf && ./configure $@