Signed overflow patches OK for 4.2?

[Ian Lance Taylor]

I'd like to backport the set of signed overflow patches for 4.2, now
that they are (almost) all in mainline.  These are the patches which
add -fstrict-overflow and -Wstrict-overflow.  It was the additional
reliance of strict signed overflow in 4.2 which led to a long
discussion a couple of months ago.

This would be a new feature for 4.2, of course.  Is it OK to do the
backport?

Thanks.

Ian