is 0ad gpl licenced?

According to this page:
The code and data are available under the GPL license, and the art, sound and documentation are available under CC-BY-SA.

http://trac.wildfiregames.com/browser#ps/trunk see the licenses there. it seems to be gpl and lgpl for some parts,

Looks like it's a mess according to http://trac.wildfiregames.com/browser/ps/trunk/LICENSE.txt with proprietary and "unspecified" licenses.

Taking a quick look at the libraries (searching the Trisquel repository if no license is explicitly mentioned), it looks like they all are free software but one: dbghelp.dll. This one, explicitly labelled "proprietary" in LICENCE.txt is for Windows only.

The files in build are small scripts with, usually, no license attached (some have a free software license, e.g., premake4). However I believe the GPL applies (why would the developers license most of the code under the GPL but the building scripts?).