Add rtc.h header file

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3493 42af7a65-404d-4744-a932-0658087f49c3

include/sys/time.h

@@ -33,8 +33,8 @@
  *
  ****************************************************************************/
 
-#ifndef __SYS_MMAN_H
-#define __SYS_MMAN_H
+#ifndef __INCLUDE_SYS_TIME_H
+#define __INCLUDE_SYS_TIME_H
 
 /****************************************************************************
  * Included Files
@@ -71,4 +71,4 @@ EXTERN int gettimeofday(struct timeval *tp, FAR void *tzp);
 }
 #endif
 
-#endif /* __SYS_MMAN_H */
+#endif /* __INCLUDE_SYS_TIME_H */

include/sys/types.h

@@ -179,6 +179,10 @@ typedef int16_t      blksize_t;
 typedef unsigned int socklen_t;
 typedef uint16_t     sa_family_t;
 
+/* Used for system times in clock ticks */
+
+typedef uint32_t     clock_t;
+
 /* The type useconds_t shall be an unsigned integer type capable of storing
  * values at least in the range [0, 1000000]. The type suseconds_t shall be
  * a signed integer type capable of storing values at least in the range