Add OemRouter facility.

OemRouter adds a facility to register OEM Group Message handlers,
then dispatch matching messages to the registered handler.
Added as a core source so that any dynamic provider can register its
messages without requiring any specific load order.

Includes code fixes for x86 portability.

Change-Id: I47b8fe7873e3c7fdf35a00d3c8a7e17d30c398c4
Signed-off-by: Peter Hanson <peterh@google.com>
Signed-off-by: Patrick Venture <venture@google.com>
9 files changed