Patch: new contrib script, auto-fetch

[Paolo Bonzini]

> +BASE=ftp://ftp.gnu.org/pub/gnu
> +AMDIR=automake-1.9.3
> +AMFILE=$AMDIR.tar.bz2
> +AUTOMAKE=$BASE/automake/$AMFILE
> +AUTOCONF=$BASE/autoconf/$ACFILE

I'd add an optional argument specifying the install directory.  One may 
reasonably want to install the autotools in $HOME or anyway to discard 
the build directory.

And I'd extract the version number from ACDIR and pass it as a program 
suffix.

Nice script!

Paolo