tests: use nanosleep instead of usleep

man usleep says that bahaviour of using usleep with SIGALRM signal
is unspecified. So create our own usleep that calls nanosleep instead.
Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

tests/display-test.c

@@ -333,6 +333,21 @@ register_reading(struct wl_display *display)
 	assert(wl_display_flush(display) >= 0);
 }
 
+#define USEC_TO_NSEC(n) (1000 * (n))
+
+/* since we are using alarm() and SIGABRT, we can not
+ * use usleep function (see 'man usleep') */
+static void
+test_usleep(useconds_t usec)
+{
+	struct timespec ts = {
+		.tv_sec = 0,
+		.tv_nsec = USEC_TO_NSEC(usec)
+	};
+
+	assert(nanosleep(&ts, NULL) == 0);
+}
+
 /* create thread that will call prepare+read so that
  * it will block */
 static pthread_t
@@ -349,8 +364,8 @@ create_thread(struct client *c, void *(*func)(void*))
 	 * so call usleep once again after the loop ends - it should
 	 * be sufficient... */
 	while (c->display_stopped == 0)
-		usleep(500);
-	usleep(10000);
+		test_usleep(500);
+	test_usleep(10000);
 
 	return thread;
 }
@@ -517,8 +532,8 @@ threading_read_after_error(void)
 
 	/* make sure thread is sleeping */
 	while (c->display_stopped == 0)
-		usleep(500);
-	usleep(10000);
+		test_usleep(500);
+	test_usleep(10000);
 
 	assert(wl_display_read_events(c->wl_display) == -1);