[xsl] Compacting with xmllint

["Ihe Onwuka ihe.onwuka@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

I'm sure most are familiar with the --format option on xmllint to get more
readable XML. I've also found it useful for compacting a large file. A file
of mine that was 92MB pre-compacting comes out at 86MB after. This could be
very handy for files like mine that are bordering on being too big to
transform.