gzip: fix cygwin build

pkgs/tools/compression/gzip/default.nix

@@ -52,6 +52,12 @@ stdenv.mkDerivation (finalAttrs: {
     sed -i '1{;/#!\/bin\/sh/aPATH="'$out'/bin:$PATH"
     }' $out/bin/*
   ''
+  # avoid wrapping the actual executable on cygwin because changing the
+  # extension will break dll linking
+  + lib.optionalString stdenv.hostPlatform.isCygwin ''
+    mv $out/bin/{,.}gzip.exe
+    ln -s .gzip.exe $out/bin/gzip
+  ''
   # run gzip with "-n" when $GZIP_NO_TIMESTAMPS (set by stdenv's setup.sh) is set to stop gzip from adding timestamps
   # to archive headers: https://github.com/NixOS/nixpkgs/issues/86348
   # if changing so that there's no longer a .gzip-wrapped then update copy in make-bootstrap-tools.nix