update libchdr

diff --git a/deps/libchdr b/deps/libchdr
index aaca599..b397465 160000 (submodule)
--- a/deps/libchdr
+++ b/deps/libchdr
@@ -1 +1 @@
-Subproject commit aaca599e18e43933fc193bd1b715c368c306208b
+Subproject commit b3974651d869c2f804e9879b063c23280d2ae617