gbox: Stop using get_module().

This reimplements commit r8364. It seems that after this commit
gbox module was broken because it can't detect its own clients.

Thanks to all that tested my patches and helped me figure it out.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8401 4b0bc96b-bc66-0410-9d44-ebda105a78c1