Proposal: run GHC API tests on fast

[Edward Z. Yang]

Currently, most GHC API tests are not run on 'make fast',
ostensibly because linking against the GHC API can take a while.
I propose that change this, and run GHC API tests by default.
Reasons:

1. The GHC API is closely tied a lot of internal structure of GHC, so
it's very easy to make a change, track it through the rest of the
compiler, but forget to update the tests/documentation.

2. We can boost this into poor man's testable documentation.  The idea
is to duplicate all GHC API examples in the manual in the test suite,
and have a comment on all of the examples asking the developer to update
the manual. (Or we could automatically extract the snippets from the
manual, but that's work and this I could do in a few minutes.)

3. I don't think running these tests will add that much extra run
time to the test suite; certainly interactively the time spent linking
is unnoticeable.

Let's set a one week discussion period for this proposal.

Thanks,
Edward