Add a preference to byte-swap the CAN ID field.

Add a preference to byte-swap the CAN ID field.

This can be useful when dealing with 1) captures from versions of
libpcap without the bug fix to use DLT_CAN_SOCKETCAN_HOSTENDIAN when
appropriate and 2) DLT_CAN_SOCKETCAN_HOSTENDIAN captures if processed by
a machine with a different byte order from the capturing machine with
software that doesn't properly put the field into host byte order when
reading and writing.

Change-Id: Ia206e5c51aecccf2508cca01cff65a4feb379ac8
Reviewed-on: https://code.wireshark.org/review/17187
Reviewed-by: Guy Harris <guy@alum.mit.edu>