bug#55026: potential prebuilt binaries in the Mono package

[zamfofex]

It seems the package for Mono in Guix uses a tarball that contains a lot of 
prebuilt DLLs. This doesn’t seem to have been mentioned when the package was 
introduced. Could it have been a mistake? Some related discussion: 
<https://github.com/mono/mono/issues/7445> and also 
<https://logs.guix.gnu.org/guix/2022-04-19.log#195614>