r189149 - Don't imply -flto with -O4.

[Rafael Espíndola]

>> We now saturate at -O3.
>
> We actually don't...-O4 still implies -fvectorize. Otherwise I would say -O4 should warn that it doesn't do anything any more, at least for one release.
>

We do the same for -O3:

$ ./build/bin/clang -c -O4 -v test.c  > o4.log 2>&1
$ ./build/bin/clang -c -O3 -v test.c  > o3.log 2>&1
$ diff o3.log  o4.log

I agree that warning at -OX with X > 3 is probably a good idea.

Cheers,
Rafael