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
. create signals-related struct message type to store sigset_t
directly
. create notify-specific message types, so the generic NOTIFY_ARG
doesn't exist anymore
. various related test expansions, improvements, fixes
. add a few error-checks to sigismember() calls
. rename kernel call specific signals fields to SYS_*
Change-Id: I53c18999b5eaf0cfa0cb25f5330bee9e7ad2b478