You cannot change the alignment without changing the ABI. The first
m68k port of gcc was using the ABI of the Sun cc, which was created for
the 68010, so alignment bigger than 2 byte was not necessary.
Thank you very much for valuable answer, now it's clear and I can't do anything with it ;-)
Btw, in the meantime I've got reply from author of vbcc -- the reason why vbcc does this in such way as well is the fact Amiga (original platform for vbcc) uses similar ABI, i.e. 2 bytes align. Again learned something new :)
Thank you everyone for clearing this thing up.