This is causing build errors for myself and a few other people.
This config option disables the SDL2 port from trying to compile
with the JACK audio server (which we don't need).
* Use ${version} instead of explicit version numbers in urls/filenames
* Move -L option to port script, as this is always good
* Fix some various other stuff
Ports/.port_include.sh, Toolchain/BuildIt.sh, Toolchain/UseIt.sh
have been left largely untouched due to use of Bash-exclusive
functions and variables such as $BASH_SOURCE, pushd and popd.
Much redundancy is removed from package scripts with this system.
It also supports simple dependency management, uninstalling (through
BSD ports style plist files), cleaning up after itself (with clean,
clean_dist, clean_all commands), etc.
