opencv: fix commit checkout

diff --git a/src/3rdparty/opencv b/src/3rdparty/opencv
index 81295513a0b90dee1d6a10604c2af4d51f4f1d20..50585e3e059f5ad806a94e9b4bc9ad599a74b169 160000 (submodule)
--- a/src/3rdparty/opencv
+++ b/src/3rdparty/opencv
@@ -1 +1 @@
-Subproject commit 81295513a0b90dee1d6a10604c2af4d51f4f1d20
+Subproject commit 50585e3e059f5ad806a94e9b4bc9ad599a74b169