Actually, at least all of:

  ansi.h aout_machdep.h asm.h cdefs.h cpu.h db_machdep.h endian.h float.h
  frame.h ieeefp.h kcore.h limits.h param.h pcb.h profile.h psl.h ptrace.h
  reg.h setjmp.h signal.h stdarg.h trap.h types.h varargs.h

should just include the version for arch/powerpc/include.  Probably 
others as well.