Add an RA_INTERFACES register action.

Add an RA_INTERFACES register action.

Add RA_INTERFACES between RA_PREFERENCES and RA_CONFIGURATION. Wireshark
was spending a suspiciously long time loading module preferences here.
(Now we just need to find out why that section of the code is slow.)

Change-Id: Iecbe55e8e10c8844bcb151a13e383cb13a3f6eb1
Reviewed-on: https://code.wireshark.org/review/16133
Reviewed-by: Anders Broman <a.broman58@gmail.com>