cmd/compile: remove flag_largemodel
It was added in 2013 in CL
7064048.
All uses of it in the compiler disappeared with
(or possibly before) the SSA backend.
Several releases have gone by without it,
from which I conclude that it is now not needed.
Change-Id: I2095f4ac05d4d7ab998168993a7fd5d954aeee88
Reviewed-on: https://go-review.googlesource.com/40856
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>