--summary (used by make check) causes ccanlint to only ever print a
one-line summary of the results.  When one of the tests fails, this isn't
very useful, because it doesn't say why it failed, or even which test
failed.  This is particularly frustrating for failures in Travis CI builds
where it's not always straightforward to reproduce a similar enough build
environment to check the failure manually for a particular module.

--summary does have one purpose which is vital for make check, though: it
suppresses any attempt to interactively correct / improve the module
printing only results.

This changes --summary to only have the second effect, not the first.  This
won't change the output in the case of passing modules, but will give more
useful information in the case of failing modules.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>