Add SCHED_SPORADIC (even though we don't use it)

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@138 42af7a65-404d-4744-a932-0658087f49c3

include/sched.h

@@ -51,9 +51,10 @@
 
 /* POSIX-like scheduling policies */
 
-#define SCHED_FIFO  1  /* FIFO per priority scheduling policy */
-#define SCHED_RR    2  /* Round robin scheduling policy */
-#define SCHED_OTHER 4  /* Not used */
+#define SCHED_FIFO     1  /* FIFO per priority scheduling policy */
+#define SCHED_RR       2  /* Round robin scheduling policy */
+#define SCHED_SPORADIC 3  /* Not supported */
+#define SCHED_OTHER    4  /* Not supported */
 
 /* Pthread definitions **********************************************************/