[Xfce-i18n] galician translation updates

[Leandro Regueiro]

>> Please don't change the ChangeLog file it caused me more conflicts
>> than easing the commit task as it should have.

Ok, sorry. I will send it today.

> How did that conflict?  Were they outdated?  If not, I don't see
> anything wrong for translators to add the changelog entry.

The problem is that I added galician to LINGUAS but there is no gl.po
for xfce4-mixer :)

Bye,
             Leandro Regueiro