Drop Windows platform for Firefox based Tor Browser

The Tor Browser is based on Mozilla's Extended Support Release (ESR) Firefox branch. Firefox is lesser of two evils, bad for security and anonymity but better than nothing. Except Windows platform, where it broken totally. Mozilla using Visual Studio (proprietary M$ poisoned closed source) software to build browser, it have no support for GCC (MinGW port) without additional patches. Nobody except Tor developers tries to produce MinGW port of browser for distribute purpose. And Tor project have no resources to support MinGW builds properly. See legacy/trac#13443 (moved) and legacy/trac#13558 (moved) for example.

Every efforts to support MinGW builds of Firefox based browser is yet more waste of resources.