bug#77793: x64dbg cannot find builtin libraries references when running on the Guix's wine

[Carlos via Bug reports for GNU Guix]

Just an update: I've found the root of this issue. The wine package 
doesn't use the mingw cross gcc to compile wine's native dlls.

To address this, we need to use gcc-cross-<arch>-w64-mingw32-toolchain 
as input for wine, as its build system will take care to find and 
automatically use it for compiling suitable things.

I'll work on a patch for it.