os_sleep: Use nanosleep for POSIX versions 2008 and higher

uClibc-ng optionally disabled deprecated POSIX functions like usleep,
causing compilation failures. This switches to nanosleep while retaining
support for older libcs that do not support nanosleep.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/utils/os_internal.c

@@ -25,10 +25,16 @@
 
 void os_sleep(os_time_t sec, os_time_t usec)
 {
+#if defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200809L)
+	const struct timespec req = { sec, usec * 1000 };
+
+	nanosleep(&req, NULL);
+#else
 	if (sec)
 		sleep(sec);
 	if (usec)
 		usleep(usec);
+#endif
 }
 
 

src/utils/os_unix.c

@@ -49,10 +49,16 @@ struct os_alloc_trace {
 
 void os_sleep(os_time_t sec, os_time_t usec)
 {
+#if defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200809L)
+	const struct timespec req = { sec, usec * 1000 };
+
+	nanosleep(&req, NULL);
+#else
 	if (sec)
 		sleep(sec);
 	if (usec)
 		usleep(usec);
+#endif
 }