[libc] move struct sigevent to libc_signal.h file.

Author: BernardXiong

components/libc/pthreads/pthread.h

@@ -276,27 +276,6 @@ int pthread_barrier_init(pthread_barrier_t           *barrier,
 
 int pthread_barrier_wait(pthread_barrier_t *barrier);
 
-/*  Signal Generation and Delivery, P1003.1b-1993, p. 63
-    NOTE: P1003.1c/D10, p. 34 adds sigev_notify_function and
-          sigev_notify_attributes to the sigevent structure.  */
-#if 0
-union sigval
-{
-    int    sival_int;    /* Integer signal value */
-    void  *sival_ptr;    /* Pointer signal value */
-};
-#endif
-
-struct sigevent
-{
-    int              sigev_notify;               /* Notification type */
-    int              sigev_signo;                /* Signal number */
-    union sigval     sigev_value;                /* Signal value */
-    void           (*sigev_notify_function)( union sigval );
-                                               /* Notification function */
-    pthread_attr_t  *sigev_notify_attributes;    /* Notification Attributes */
-};
-
 /* posix clock and timer */
 #define MILLISECOND_PER_SECOND  1000UL
 #define MICROSECOND_PER_SECOND  1000000UL

components/libc/signal/posix_signal.h

@@ -97,7 +97,6 @@ struct sigevent {
   int sigev_signo;
   union sigval sigev_value;
 
-
   void (*sigev_notify_function)( union sigval );
 
   pthread_attr_t *sigev_notify_attributes;

include/libc/libc_signal.h

@@ -30,12 +30,26 @@
 extern "C" {
 #endif
 
+/*  Signal Generation and Delivery, P1003.1b-1993, p. 63
+    NOTE: P1003.1c/D10, p. 34 adds sigev_notify_function and
+          sigev_notify_attributes to the sigevent structure.  */
+
 union sigval 
 {
     int    sival_int;    /* Integer signal value */
     void  *sival_ptr;    /* Pointer signal value */
 };
 
+struct sigevent
+{
+    int          sigev_notify;               /* Notification type */
+    int          sigev_signo;                /* Signal number */
+    union sigval sigev_value;                /* Signal value */
+    void         (*sigev_notify_function)( union sigval );
+                                             /* Notification function */
+    void         *sigev_notify_attributes;   /* Notification Attributes, really pthread_attr_t */
+};
+
 struct siginfo
 {
     rt_uint8_t si_signo;