r189369 - Warn that -O4 is the same as -O3.

[Rafael Espíndola]

> Any reason not to remove this, and instead look at the argument to the OPT_O
> option?
>
> (Likewise, why do we have a separate -O0 flag?)

Just convenience. It is easier to write

A->getOption().matches(options::OPT_O4)

Than to check it matches OPT_O, get the value, check if it is integer and == 4.

Cheers,
Rafael