Use Qt::TimerType on UNIX when scheduling timers

Use Qt::TimerType on UNIX when scheduling timers

As stated in the documentation for Qt::TimerType, we allow for up to
5% error for CoarseTimers (the default timer type). PreciseTimers are
not adjusted at all, and VeryCoarseTimers fire with one-second accuracy.
The objective is to make most timers wake up at the same time, thereby
reducing CPU wakeups.

Note that this changes makes it possible for timers to fire early, which
may be unexpected for some applications. Such applications should use
PreciseTimers explicitly.

Author: Thiago Macieira <thiago.macieira@nokia.com>
Change-Id: Iaa70314c39a446adbc6dbb6fdfa7bafcd98a7283
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>