udev: rules - ignore the lack of trailing newline

Also accept '\r' as newline character.

This dropps warnings of the type:

  invalid key/value pair in file /usr/lib/udev/rules.d/40-usb-media-players.rules
  on line 26, starting at character 25 ('')

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
udev: strings in C are NUL-terminated anyway, no need to add a second NUL...

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>