[Cython] Test runner

[mark florisson]

Another, different but related issue: how can we get useful output
from the test runner? e.g. I'm running my test with a
'@cython.test_assert_path_exists("...")' and I get this error output:

======================================================================
ERROR: runTest (__main__.CythonRunTestCase)
compiling (c) and running parallel
----------------------------------------------------------------------
Traceback (most recent call last):
  File "runtests.py", line 555, in run
    self.runCompileTest()
  File "runtests.py", line 386, in runCompileTest
    self.test_directory, self.expect_errors, self.annotate)
  File "runtests.py", line 532, in compile
    self.assertEquals(None, unexpected_error)
AssertionError: None != u'9:0: Compiler crash in TreeAssertVisitor'

So I'm seeing a traceback from the test runner (which I'm not really
interested in :), but the actual traceback is not displayed.

Can I also specify special link and compiler flags for a certain test,
like in http://wiki.cython.org/enhancements/distutils_preprocessing ?
Or do I have to export LDFLAGS and CFLAGS in my environment?