This apparently made no difference before, but it looks like I fixed
it in my time overhaul, which made this test suddenly run a lot
slower.

This reverts commit 0114212f8588211d3dd6735d55127bce2cc1dad7.

This fix is very wrong, but I'm drowning in optllvm failures and need
to fix this ASAP (it's somewhat suboptimal that I won't be able to run
the LLVM tests here until I upgrade the OS or install a later LLVM
manually).

Should improve startup time of make in the testsuite, and it is
simpler.

I think this didn't show up before with --fast?

The instance-leaks test is now gone, as we now expect the instances to
leak into haskell98.

Conflicts:
	tests/typecheck/should_run/all.T

major TcErrors refactoring

I checked and there's no regression here, just timing of GCs.

OVERALL SUMMARY for test run started at Fri Jan  6 09:46:46 GMT 2012
      82 total tests, which gave rise to
     820 test cases, of which
       0 caused framework failures
     818 were skipped

       0 expected passes
       2 had missing libraries  <---
       0 expected failures
       0 unexpected passes
       0 unexpected failures