Update gvc

diff --git a/src/gvc b/src/gvc
index 3d6aac673b88fff548db57a75b82e8f14723c1fe..6826d0a5fe172325cec946244d1ea6590143a03e 160000 (submodule)
--- a/src/gvc
+++ b/src/gvc
@@ -1 +1 @@
-Subproject commit 3d6aac673b88fff548db57a75b82e8f14723c1fe
+Subproject commit 6826d0a5fe172325cec946244d1ea6590143a03e