[AD] Version check patch

[Chris <chris.kcat@xxxxxxxxxx>]

Attached is a crude patch that enables install_allegro to check the 
program's version against the library's, and fail if they don't match.

So you don't have to go through digging through the patch to figure it 
out, this is what I did. First, I renamed install_allegro to 
_install_allegro and added _get_allegro_version. Then I added the 
MAKE_VERSION macro to create the version numbers to check against. 
Finally, I added a static inline install_allegro in system.h which 
checks the version returned by _get_allegro_version with the version 
being compiled before calling _install_allegro.

Attachment: ver_check.diff.gz
Description: application/gzip