Update: Rewrite the enabled/disabled logic for the install.sh script.

Update: Rewrite the enabled/disabled logic for the install.sh script.

The --disable-shared/--disable-static should override --enable-shared-program/--enable-static-program (and similar).

Apply build_shared and build_static if and only if shared/static parameters are not specified.

Fix minor bug where wrong string is printed when an error is supposed to be printed.
The code is printing $build_shared when it should be printing $path_shared.
The code is printing 'library' in cases that should print 'program'.

$build_shared and $build_static no longer need to be directly tested for.
This testing happens when checking and guaranteeing the individual program/library shared/static state.