Lexer: don't care if end of comment is followed by a newline.

Lexer: don't care if end of comment is followed by a newline.

re2c used to swallow newline that immediately followes end of directive:
for most of the directives re2c generates code block that ends with a
newline, so the generated code looks better if the newline is not doubled.

However, this unnecessarily complicates the lexer.