Update MuJS submodule to version 1.0.9.

diff --git a/thirdparty/mujs b/thirdparty/mujs
index 6a9eedea88d4194407f8c0a578e4458f73b7364d..6871e5b41c07558b17340f985f2af39717d3ba77 160000 (submodule)
--- a/thirdparty/mujs
+++ b/thirdparty/mujs
@@ -1 +1 @@
-Subproject commit 6a9eedea88d4194407f8c0a578e4458f73b7364d
+Subproject commit 6871e5b41c07558b17340f985f2af39717d3ba77