[basm] Include once does not behave propelry when using relative path named differently that point to the same file

[rgiot]

If once file does

    include once 'src/config.asm'
    include once 'src/demosystem/public.asm'

Whereas another one does

    include once "../config.asm"
    include once '../demosystem/public.asm'

but the files are striclty the same absolute one, the inclusion is done two times.
The appropriate behavior is to include it one time.

relative to absolute file naming is expected I guess