[AD] Verbose output from init() routines

[Jon Rafkind <workmin@xxxxxxxxxx>]

Occasionally I wonder what Allegro is doing during the init() routines 
and rather than hack the source to make it display these things I think 
it would be convienent to have some way to make Allegro do this for me.
One way is to have an extra parameter for each init routine. This is 
good for multi-threading but bad for backwards compatibility and 
besides, Allegro is hardly multi-threadable.

The other way is to have a global variable, allegro_verbose or 
allegro_debug, that when set to a non-zero value would make the init() 
routines printf() some stuff to the screen. Maybe for higher values of 
the variable the init() routines will be even more verbose.

Just wanted to throw the idea out there before I write some code.