salsa20/salsa: eliminate unnecessary "callee save" prologue/epilogue
salsa20/salsa: eliminate unnecessary "callee save" prologue/epilogue

SP offsets were adjusted to fill in the now unused callee save area
using the following Python script:

import sys, re
def adj(m):
    delta = int(m.group(1))
    if delta >= 408:
        delta -= (408 - 352)
    return "%d(SP)" % delta
sys.stdout.write(re.sub(r"(\d+)\(SP\)", adj, sys.stdin.read()))

Change-Id: I06675a75d89e5834f804df595868fe4bb8976719
Reviewed-on: https://go-review.googlesource.com/31587
Run-TryBot: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@golang.org>

golang/crypto,golang/crypto,golang/crypto,ScriptRock/crypto,ScriptRock/crypto