More fine-grained compilation stats

[LebedevRI]

Not sure if this is the correct place for this issue, but here it goes.
It would be good to see more detailed overview of the back-end phase.
In particular, it would be great to have at least global **** Passes that took longest:
Possibly something more fine-grained too (top-10 pass-function, pass-files pairs e.g.)

[LebedevRI]

Aha, and there already is OptFunction in OptPass; with RunPass'es that either a proper pass
(with a name in details), or containing RunLoopPass (also with name in details).
So this appears to be mostly the right place for this issue report.

[aras-p]

Yeah, will add that at some point. Busy with unrelated stuffs right now!