Make it easier for other people to use the script and change version
to SDL 2.0.8.
* Add directions for how to use the script.
* Add ability to specify directory for where to store my SDL builds.
* Add automatic downloading of my SDL builds and fix prefix path in
sdl2-config.
* Copy libSDL2-2.0.so.0 to the build directory like Windows and macOS
do in the Makefile.
* Automatically find the required glibc version after compiling.
Zack Middleton
Zack Middleton