ticket #4370

In the testsuite there are numerous Makefiles that invoke $(TEST_HC).
But, unlike the tests invoked directly by the harness, they didn't pass
-dno-debug-output, or $(EXTRA_HC_OPTS).

This patch goes part-way towards the goal of making the two consistent:

* Almost all invocations in the Makefiles now go
    '$(TEST_HC)' $(TEST_HC_OPTS)

* In test.mk we initialise
     TEST_HC_OPTS = -dno-debug-output $(EXTRA_HC_OPTS)

Still to come (I don't know how to do these)

* The invocations of TEST_HC via cabal are not treated
  (eg cabal01, cabal04), and they should be

* TEST_HC_OPTS should probably be initialised the same way
  as the Python script computes the flags to pass to the
  TEST_HC that it calls directly

... so that we test the coercion optimiser

We now need to import Data.Char rather than Char.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

Rename the auxiliary module to work on case-insensitive filesystems,
and add extra-cleans for it.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

The following test creates a nice, inner loop inside a procedure with
the new code generator, which tickles the invariant in CmmOpt that
all temporaries are single assignment and also a register allocator bug.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

* 'trac_5025' of https://github.com/thoughtpolice/testsuite:
  Tests for trac #5025.