During C compiler feature testing, the `main` function was defined
with a parameter list of `(int argc, char *argv [])` but these
parameters were not used. This results in compiler warnings when
the generated file is compiled with the `-Wextra` warning flag
added to the `cc-options` of the cabal file.

Reviewers: hvr, RyanGlScott, bgamari, rwbarton

Reviewed By: rwbarton

Differential Revision: https://phabricator.haskell.org/D2677