* 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
Squashed commit of the following:
graphics/: Rename nxfe_reportposition to nxmu_reportposition. The is no longer an nxfe layer.
graphics/: Renmae nxfe_redrawreq to nxmu_redrawreq. The is no longer an nxfe layer.
graphics/nxmu/nxmu.h: Renmae nxfe.h to nxmu.h. There is no long an nxfe layer.
graphics/: Rename nxfe_state_s to nxmu_state_s. There is no longer an nxfe layer.
graphics/: Rename nxfe_conn_s to nxmu_conn_s. There is no longer an nxfe layer.
