message: build: make macOS HOST in download-osx generic
  This was missed in and the update before that, so just
  make this un-versioned so that we don't have to worry about it.
  This is fine, because it's just for downloading sources.
diff: @@ -265,7 +265,7 @@ install: check-packages $(host_prefix)/share/config.site
  download-one: check-sources $(all_sources)
  download-osx:
  - @$(MAKE) -s HOST=x86_64-apple-darwin14 download-one
  + @$(MAKE) -s HOST=x86_64-apple-darwin download-one
  download-linux:
  @$(MAKE) -s HOST=x86_64-unknown-linux-gnu download-one
  download-win:
  