Remove unused fork implementations

[Roland McGrath]

> That leaves sysdeps/unix/sparc/sysdep.h which is used, by:
> 
> 	sysdeps/unix/sysv/linux/sparc/sparc32/sysdep.h
> 	sysdeps/unix/sysv/linux/sparc/sparc64/sysdep.h
> 
> Should I move the contents of sysdeps/unix/sparc/sysdep.h into
> sysdeps/sparc/sysdep.h?
> 
> The PIC bits are OS neutral, but the system call stuff is "UNIX"
> specific.
> 
> So, maybe put the PIC bits into sysdeps/sparc/sysdep.h and put the
> syscall stuff into sysdeps/unix/sysv/linux/sparc/sysdep.h?

Each area of code should be in the least-specific sysdeps directory to
which it applies.  So moving things purely about writing sparc machine
code into sysdeps/sparc/ is right.  If the syscall stuff applies to how
syscalls are done on other sparc systems like BSDs, then leave it in
sysdeps/unix/sparc/.


Thanks,
Roland