* sysdeps/powerpc/powerpc32/sysdep.h: New file. Define powerpc32
specific macros copied from sysdeps/powerpc/sysdep.h.
* sysdeps/powerpc/powerpc64/sysdep.h: New file. Define powerpc64
specific macros.
* sysdeps/unix/powerpc/sysdep.h: Include <bits/wordsize.h>.
[__WORDSIZE==64]: Include sysdeps/powerpc/powerpc64/sysdep.h.
[!__WORDSIZE==64]: Include sysdeps/powerpc/powerpc32/sysdep.h.