Add more NX name space fixups

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1377 42af7a65-404d-4744-a932-0658087f49c3

arch/sim/src/nuttx-names.dat

@@ -24,11 +24,13 @@ rewinddir    NXrewinddir
 rmdir        NXrmdir
 seekdir      NXseekdir
 select       NXselect
+sleep        NXsleep
 socket       NXsocket
 stat         NXstat
 statfs       NXstatfs
 system       NXsystem
 umount       NXumount
 unlink       NXunlink
+usleep       NXusleep
 write        NXwrite
 zmalloc      NXzmalloc