updated libgcj version

Following the aur comment by neo01,
I've updated the version we download from debian. from _9 to _10

BTW, to find the md5sums I've used

    curl http://ftp.de.debian.org/debian/indices/md5sums.gz |zcat |grep libgcj14_4.8.1-10_

But I've also verified the md5sums myself.
Merge pull request #8 from jarondl/libgcj14_4.8.1-10

libgcj: update version