On SMP systems there isn't a need for all dahdi timers to
synchronize on dahdi_timer_lock. Instead give each timer it's own
lock to synchronize with process_timers and use dahdi_timer_lock to
protect the global list of locks.
Also, the dahdi_timers list now only contains timers that are set to
fire. This eliminates a test for each timer in the hot path of the
process_masterspan context.
Reduces system load on many-core systems which are heavy users of
DAHDI timers.
Internal-Issue-ID: ABE-2904
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
b6f6232441