ports/140879: new port graphics/gimp-save-for-web

[Grzegorz Blach]

I try build gimp-save-for-web in clean jail, starting without any ports.
And it build fine (also build 222 other ports as dependency).

I don't known why can't find p5-XML-Parser in your report.

So I added as port-dependency p5-XML-Parser (but on my jail this was
build as dependency of dependency).

Locale dir I changed with:
USE_GNOME=      gnomehack gnometarget


I also added WWW in descr.