PowerPC: Consolidate NPTL/non versions of vfork
PowerPC: Consolidate NPTL/non versions of clone
PowerPC: Move powerpc64 timer_*.c out of nptl/
PowerPC: Move NPTL ABI headers to sysdeps.
PowerPC: Move remaining nptl/sysdeps/unix/sysv/linux/powerpc/ files.
Update powerpc-fpu ULPs.