changing "configure" to default to "gcc -g -O2 -fwrapv ..."

[Robert Dewar]

Ian Lance Taylor wrote:

> The new option -fstrict-overflow tells gcc that it can assume the
> strict signed overflow semantics prescribed by the language standard.
> This option is enabled by default at -O2 and higher.  Using
> -fno-strict-overflow will tell gcc that it can not assume that signed
> overflow is undefined behaviour.  The general effect of using this
> option will be that signed overflow will become implementation
> defined.  This will disable a number of generally harmless
> optimizations, but will not have the same effect as -fwrapv.

Can you share the implementation definition (implementation defined
generally means that the implementation must define what it does).
This seems awfully vague.