posix: pthread: pthread_mutex_timedlock should accept absolute deadline

It was coded as if it accepts relative timeout. Normative reference:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_timedlock.html

Signed-off-by: Paul Sokolovsky <[email protected]>

Author: pfalcon

include/posix/pthread.h

@@ -224,7 +224,7 @@ int pthread_mutex_unlock(pthread_mutex_t *m);
  */
 
 int pthread_mutex_timedlock(pthread_mutex_t *m,
-			    const struct timespec *to);
+			    const struct timespec *abstime);
 
 /**
  * @brief POSIX threading compatibility API

lib/posix/pthread_mutex.c

@@ -9,6 +9,8 @@
 #include <wait_q.h>
 #include <posix/pthread.h>
 
+s64_t timespec_to_timeoutms(const struct timespec *abstime);
+
 #define MUTEX_MAX_REC_LOCK 32767
 
 /*
@@ -73,9 +75,10 @@ int pthread_mutex_trylock(pthread_mutex_t *m)
  * See IEEE 1003.1
  */
 int pthread_mutex_timedlock(pthread_mutex_t *m,
-			    const struct timespec *to)
+			    const struct timespec *abstime)
 {
-	return acquire_mutex(m, _ts_to_ms(to));
+	s32_t timeout = (s32_t)timespec_to_timeoutms(abstime);
+	return acquire_mutex(m, timeout);
 }
 
 /**