Don't include trailing newline in comment token

Don't include trailing newline in comment token

Don't include a trailing newline in T_COMMENT tokens, instead leave
it for a following T_WHITESPACE token. The newline does not belong
to the comment logically, and this makes for an ugly special case,
as other tokens do not include trailing newlines.

Whitespace-sensitive tooling will want to either forward or backward
emulate this change.

Closes GH-5182.