[AD] new ppc directory under src

[ronaldo h. y. <r.y...@uo...>]

i am working on some assembler routines _hline8 and _vline8 i could create a
new directory under src or put the files in mac directory?

the routines could be used in some PowerPC future plataforms like Unix,
PPCLinux, AIX, PPCBeOS.
the routines work only work with linear bitmap (memory mapped, no bank
switch).
the routines aren't optimised for 64-bit(g3,g4).