(init): Take just one arg, DATA for the entry SP; DATA[-1] is always the

(init): Take just one arg, DATA for the entry SP; DATA[-1] is always the
return address location.  In both cthreads and non-cthreads cases, use asm
to force parameters into %eax and %ecx before return, and mutate DATA[-1]
to return to specific asm code to set up the user from %eax and %ecx.
[PIC] (_init): Caller changed.
(__libc_init_first) [! PIC] (doinit): Use asm to effect call to init
with SP unwound to argument data ptr.