These patches were originally found at the debian mingw-w64 team's
mingw-w64 repo, and should improve the reproducibility of our mingw-w64
toolchain.
* gnu/packages/patches/mingw-w64-dlltool-temp-prefix.patch: New file.
* gnu/packages/patches/mingw-w64-reproducible-gendef.patch: New file.
* gnu/local.mk (dist_patch_DATA): Update accordingly.
* gnu/packages/mingw.scm (make-mingw-w64): Apply patches.
