Fix constant folding of overflows

This suppresses some byte-code optimizations that were invalid in
the presence of integer overflows, because they meant that .elc
files assumed the runtime behavior of the compiling platform, as
opposed to the runtime platform.  Problem reported by Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2018-03/msg00753.html
* lisp/emacs-lisp/byte-opt.el (byte-opt--portable-max)
(byte-opt--portable-min): New constants.
(byte-opt--portable-numberp, byte-opt--arith-reduce)
(byte-optimize-1+, byte-optimize-1-): New functions.
(byte-optimize-plus, byte-optimize-minus, byte-optimize-multiply)
(byte-optimize-divide):	Avoid invalid optimizations.
(1+, 1-): Use new optimizers.
(byte-optimize-or, byte-optimize-cond): Simplify by using
remq instead of delq and copy-sequence.
1 job for feature/gnus-select in 5 minutes and 47 seconds
latest
Status Job ID Name Coverage
  Test
failed #281
test

00:05:47

 
Name Stage Failure
failed
test Test
exec-shield in etc/PROBLEMS for more information.
**************************************************
20130368 of 33554432 static heap bytes used
make[1]: *** [bootstrap-emacs] Segmentation fault (core dumped)
Makefile:745: recipe for target 'bootstrap-emacs' failed
make[1]: Leaving directory '/builds/tzz/emacs/src'
make: *** [src] Error 2
Makefile:418: recipe for target 'src' failed
ERROR: Job failed: exit code 1