winePackages: enable mingwSupport in base build

With mingwSupport enabled, Wine uses MinGW builds of GCC (compiled for
the i686-w64-mingw32 & x86_64-w64-mingw32 targets) to cross compile
system DLLs as PE executables.

This is used to workaround some basic anticheat software. (See #103102)

Fedora & Arch Linux also have this enabled by default in their Wine builds:
- Fedora: 8e216ca407/f/wine.spec (_116)
- Arch Linux: 2435e762ea/trunk/PKGBUILD (L44)

pkgs/top-level/wine-packages.nix

@@ -27,6 +27,7 @@ rec {
     xineramaSupport = true;
     xmlSupport = true;
     sdlSupport = true;
+    mingwSupport = true;
   };
 
   full = base.override {