Fix test driver python3 compatibility issues

Summary:
Fixes python3 compatibility issues by replacing filter with a list
comperhension and a potential issue with python2 when override_flags
would be an empty list.

Reviewers: austin, thomie

Reviewed By: austin, thomie

Subscribers: thomie, carter, simonmar, mlen

Differential Revision: https://phabricator.haskell.org/D399

GHC Trac Issues: #9230
Add notes on change to hGetContents semantics

Summary:
Additionally, move Unicode 7.0 update notice from the compiler
section to the base libraries section.

Reviewers: austin

Reviewed By: austin

Subscribers: thomie, carter, simonmar

Projects: #ghc

Differential Revision: https://phabricator.haskell.org/D401
Fixed missing trailing newline bug in pretty printer

Summary:
Pretty printer didn't produce trailing newline in strings in error
messages.

Reviewers: simonpj, austin

Reviewed By: austin

Subscribers: thomie, carter, simonmar, mlen

Differential Revision: https://phabricator.haskell.org/D405

GHC Trac Issues: #9681
Updated testsuite/.gitignore to exclude some test artifacts on Windows.

Reviewers: austin

Reviewed By: austin

Subscribers: thomie, carter, simonmar

Differential Revision: https://phabricator.haskell.org/D404
Drop deprecated `OverlappingInstances` from base

With #9242 the `OverlappingInstances` extension got deprecated, this
commit adapts the only two remaining places in `base` where it was still
used.

Starting with this commit, the `Typeable (s t)` instance (which seemingly
was the motivation for using `OverlappingInstances` in the first place
when `Typeable` was neither polykinded nor auto-derived-only, see also
commit ce3fd0e02826367e6134a3362d8d37aa114236f5 which introduced
overlapping instances) does no longer allow overlapping instances, and
there doesn't seem to be any good reason to keep allowing overlapping
instance now.

This also removes redundant `LANGUAGE`/`OPTIONS_GHC` pragmas from
`Data.Typeable` and refactors the language pragmas into more uniform
single-line pragmas.

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D377