Windows builds, GPL compliance

[szykula]

This one relates to #730 and myriad others. The Windows builds don't work and, frankly, can't - the Windows-related source code is patchy, CMakeLists.txt does not include all the necessary files, and the entire codebase feels somewhat abandoned. The official binaries, though, are perfectly functional, which leads me to believe that not all the changes made to the project have been published. Moreover, I've decompiled the relevant parts, and - sure enough - there are some discrepancies.
The DSL support keeps ignoring my messages, so IMO they've lost the benefit of the doubt. The project is licensed under GPL and derives from GPL-licensed Sigrok but ignores GPL's terms.

[szykula]

I assume @uwehermann might be interested, no matter how dead inactive Sigrok seems to be nowadays