Start new line if \r and dialect is postgres

[hansott]

Currently the tokenizer throws an error for

insert into cats_2 (petname) values ('foo'),--\r(version()||'\n');

this is because postgres treats \r as a separate new line character, see https://github.com/postgres/postgres/blob/master/src/backend/parser/scan.l

In order to make the world safe for Windows and Mac clients as well as Unix ones, we accept either \n or \r as a newline.
A DOS-style \r\n sequence will be seen as two successive newlines, but that doesn't cause any problems.
non_newline [^\n\r]
comment ("--"{non_newline}*)

Let's make sure we start a new line if we encounter a \r when tokenizing a comment.