[COMMITTED PATCH] Fix powerpc fork after i386 reorganization.

[Roland McGrath]

> There's at least one piece done for ARM but missing for x86_64: moving the 
> ABI baselines from sysdeps/unix/sysv/linux/x86_64/{64,x32}/nptl out of the 
> nptl subdirectory.

Yes, I have not finished x86 yet.