All of these patches did the same thing, which is already in upstream
config.sub.
With this change, we need only add `use_fresh_config_sub=true` to
the package.sh file.
Note that this is not done automatically in case the port has a modified
config.sub file.
The configure script for `SDL2_mixer` was trying to find the shared
library for `libmodplug` in the wrong directories and with the wrong
filename. This installs the shared library as `libmodplug.so.1` and
symlinks to it from `libmodplug.so`, and instructs the `SDL2_mixer`
build to search for it in `/usr/local/lib`.
Fixes the build for ports Super-Mario, freeciv and dungeonrush.
