This change prevents tickless idle mode potentially sleeping for an extra tick in...

This change prevents tickless idle mode potentially sleeping for an extra tick in the corer case that a tick interrupt occurred between the scheduler being suspended and the expected idle time being checked for a second time (within the idle task) - as described by the sequence below.  Th change updates eTaskConfirmSleepModeStatus() to specifically check if a tick is pending, and if so, abort entering sleep mode.

+ The idle task decides to enter sleep mode on the following line.
```
if( xExpectedIdleTime >= configEXPECTED_IDLE_TIME_BEFORE_SLEEP )
```

+ The scheduler is suspended, preventing any context switches.

[Potentially a tick interrupt could occur here.  That could happen if other tasks executing consumed a lot of time since the above code line executed.  If a tick interrupt occurs here the interrupt will be entered but the interrupt will not do anything other than increment xPendedTicks.]

+ The expected idle time is checked again.  No context switches can occur now so the code will execute until the scheduler is unsuspended.  Assuming configEXPECTED_IDLE_TIME_BEFORE_SLEEP is set to a sensible value, a tick interrupt won't occur for some time.

+ portSUPPRESS_TICKS_AND_SLEEP() is called.

+ The default implementation of the tickless function calls eTaskConfirmSleep() - which prior to this change does not return eAbortSleep even though xPendedTicks is not 0, and after this change does return eAbortSleep.