[C2hs] PATCH: using standard Data.FiniteMap gives 6% performance improvement

Attached is a patch to c2hs 0.13.4 to convert from using the FiniteMaps and Sets modules that are included in the CTK to using the standard Data.FiniteMap and Data.Sets modules. This means less code needs to be distributed with c2hs and gives about 6% improvement in runtime (tested on gtk/gtk.h). The patch touches a few files but is pretty small, only one or two functions have different names or argument orders between the two FiniteMap versions. Duncan