* Simplify EINTR/ECANCEL error handling
1. Add semaphore uninterruptible wait function
2 .Replace semaphore wait loop with a single uninterruptible wait
3. Replace all sem_xxx to nxsem_xxx
* Unify the void cast usage
1. Remove void cast for function because many place ignore the returned value witout cast
2. Replace void cast for variable with UNUSED macro
graphics/nxterm: Needs to clear display initially. Otherwise, garbage from previous display may still be present from preceding NxWM window.
graphics/nxterm: Back out most of the preceding NxTerm changes related to window size. apps/examples/nxterm passed the complete NxTK window size. Those changes were needed to make aps/examples/nxterm work. But NxWM passes the the size of the NxTK main sub-window. So I needed to back out the changes and then change the applications so that they passed the same value (the size of the NxTK sub-window).
