First stab at making ./validate less verbose

Authored by austin.

Description

First stab at making ./validate less verbose

Summary:
When we run ./validate, we are typically given an incredibly large
heap of information, a large majority of which isn't really
necessary. In particular, we don't really care about what make is
doing, nor ghc itself most of the time.

This reduces some of the output by making ./validate quietier. By
running:

$ ./validate --quiet

you'll enable V=0 in the build, suppressing compiler messages, and
you will suppress make commands by running make in 'silent
mode'. It also runs the testsuite with VERBOSE=2 to avoid extra
lines. This alone makes quite a difference for build log sizes.

Furthermore, by making the build logs less verbose, life is easier for
systems like Harbormaster and Travis-CI, which dislike dealing with
logs that are 10k lines or more.

Signed-off-by: Austin Seipp <austin@well-typed.com>

Test Plan: iiam

Reviewers: hvr, nomeata, ezyang

Reviewed By: ezyang

Subscribers: simonmar, ezyang, carter, thomie

Projects: GHC

Differential Revision: https://phabricator.haskell.org/D298

Details