Improve the reporting of module cycles, to give a nice message like this
[ghc-hetmet.git] / compiler / stranal /
drwxr-xr-x   ..
-rw-r--r-- 46149 DmdAnal.lhs
-rw-r--r-- 17401 WorkWrap.lhs
-rw-r--r-- 19494 WwLib.lhs