Allow comments in the middle of statements to be on their own line.

This fixes llvm.org/PR14860.

Before, we messed up the format of:
if (DeclaratorInfo.isFunctionDeclarator() &&
    //getDeclSpecContextFromDeclaratorContext(Context) == DSC_top_level &&
    Tok.is(tok::semi) && NextToken().is(tok::l_brace)) {
}