Don't report unclosed comments as "no newline at end of file". If we get EOF in the "middle" of a line but there's a newline at the end of the buffer we've got, it's because we're in the middle of a comment. So, say so.

#define C(x) //**/* x */**//
C(3)
C(abc /* def */ ghi)

#define D(x) ///**/**/**///**/* x */**///**/**/**///
D(3)
D(abc /* def */ ghi)