Ensure timeout tests wait for the entire specified duration

tests/basic/timeout_config.inc

@@ -4,8 +4,8 @@ $t = 3;
 
 function busy_wait($how_long)
 {
-	$until = time() + $how_long;
+	$until = microtime(TRUE) + $how_long;
 
-	while ($until > time());
+	while ($until > microtime(TRUE));
 }