pthread: Correct default schedule policy

include/nuttx/pthread.h

@@ -51,11 +51,17 @@
 
 /* Default pthread attribute initializer */
 
+#if CONFIG_RR_INTERVAL == 0
+#  define PTHREAD_DEFAULT_POLICY SCHED_FIFO
+#else
+#  define PTHREAD_DEFAULT_POLICY SCHED_RR
+#endif
+
 #ifdef CONFIG_SCHED_SPORADIC
 #  define PTHREAD_ATTR_INITIALIZER \
   { \
     PTHREAD_DEFAULT_PRIORITY, /* priority */ \
-    SCHED_RR,                 /* policy */ \
+    PTHREAD_DEFAULT_POLICY,   /* policy */ \
     PTHREAD_EXPLICIT_SCHED,   /* inheritsched */ \
     0,                        /* low_priority */ \
     0,                        /* max_repl */ \
@@ -67,7 +73,7 @@
 #  define PTHREAD_ATTR_INITIALIZER \
   { \
     PTHREAD_DEFAULT_PRIORITY, /* priority */ \
-    SCHED_RR,                 /* policy */ \
+    PTHREAD_DEFAULT_POLICY,   /* policy */ \
     PTHREAD_EXPLICIT_SCHED,   /* inheritsched */ \
     PTHREAD_STACK_DEFAULT,    /* stacksize */ \
   }