GitLab

All to support Trac #2431

- RankN1 was a bogus test.  There error didn't have anything to do with
  rank-n types, but was just due to an ambiguous signature.

This makes things more robust when running with threads

- Two tricky tests by Tom Schrijvers and Martin Sulzmann

The remaining validation test failures on the stable branch will be
fixed by pending merged.

Its really a testsuite-framework bug that these mentions of 'opt' have
lingered so long.  They should have been rejected as a non-existent way.

Now instead of saying, e.g.
    namebase_if_compiler_lt('ghc','6.9', 'foo-6.8')
you say
    if_compiler_lt('ghc','6.9', namebase('foo-6.8'))

The test program should be rejected but not with a panic. I haven't added a
.stderr file because I don't know what the error message should be.

- Mostly changed error messages
- 'while' needs another type annotation due to changed rules as to what
  annotations are required for GADTs.