Treat CR-LF at the end of a line like LF.

That way, if we're reading a Windows-format file on UN*X, we handle it
the same way we'd handle a UN*X-format file.

This handles bug 10272 for the preference file and the "recent" files;
there are other configuration files that may need code changes as well.

Change-Id: Iec15a8fac276929ce8b53ae16070e9f2855f574c
Reviewed-on: https://code.wireshark.org/review/3042
Reviewed-by: Guy Harris <guy@alum.mit.edu>