ARM: Consolidate NPTL/non versions of vfork
x86: Consolidate NPTL/non versions of vfork
Move NPTL public ABI headers for x86 to sysdeps/x86/nptl/.
x86: Consolidate NPTL/non versions of clone
Move x86_64 timer_*.c out of nptl/
Move x86_64 compat-timer.h out of nptl/
x86_64: Remove useless pthread_spin_{init,unlock} wrapper files.
Update s390 timer_*.c files for x86_64 file moves.