This allows us to write things like this:
message m;
m.m_notify.interrupts = new_value;
or
message *mp;
mp->m_notify.interrupts = new_value;
The shorthands macro have been adapted for the new scheme, and will be
kept as long as we have generic messages being used.
Change-Id: Icfd02b5f126892b1d5d2cebe8c8fb02b180000f7
175d3e7eae