EPOLLWAKEUP handling in minui/events.c

Older trees may not have EPOLLWAKEUP defined so we will work
around the lack of EPOLLWAKEUP support as best we can. This should
only maybe affect how charger handles waking up the screen in off
mode charging in older trees. No impact on TWRP itself.

Change-Id: Ia72ebfc12778b2bcda648edc27d2092c2ead415c