Add time_update().

test/unit/time.c

@@ -0,0 +1,23 @@
+#include "test/jemalloc_test.h"
+
+TEST_BEGIN(test_time_update)
+{
+	struct timespec ts;
+
+	memset(&ts, 0, sizeof(struct timespec));
+
+	assert_false(time_update(&ts), "Basic time update failed.");
+
+	/* Only Rip Van Winkle sleeps this long. */
+	ts.tv_sec += 631152000;
+	assert_true(time_update(&ts), "Update should detect time roll-back.");
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_time_update));
+}