Show note for -Wmissing-prototypes for functions with parameters

Summary:
There was a search for non-prototype declarations for the function, but
we only showed the results for zero-parameter functions. Now we show the
note for functions with parameters as well, but we omit the fix-it hint
suggesting to add `void`.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D62750

llvm-svn: 363748