(byte-compile-butlast): Move up in file.

(byte-compile-butlast): Move up in file.
(byte-optimize-plus): Don't call
byte-optimize-delay-constants-math (bug#1334).  Use
byte-optimize-predicate to optimize constants.
(byte-optimize-minus): Don't call
byte-optimize-delay-constants-math.  Remove zero arguments first
if possible.  Call byte-optimize-predicate to optimize constants.
(byte-optimize-multiply): Remove optimizations for arguments of 0
and 2, which may be inaccurate.  Optimize (* x -1) to (- x).  Call
byte-optimize-predicate.
(byte-optimize-divide): Leave runtime errors unchanged.
Optimize (/ x 1) to (+ x 0). Remove optimizations for arguments of
0 and 2.0, which may be inaccurate.  Call byte-optimize-predicate.