bsdiff: bump submodule, pick up fix for CVE-2014-9862

This updates the bsdiff submodule to latest upstream revision, in
order to pick up additional bound checks for CVE-2014-9862.

Update submodule: bsdiff
Ref:
 * https://www.x41-dsec.de/lab/advisories/x41-2020-006-bspatch/

diff --git a/bsdiff b/bsdiff
index 1edf9f656850c0c64dae260960fabd8249ea9c60..b817e9491cf7b8699c8462ef9e2657ca4ccd7667 160000 (submodule)
--- a/bsdiff
+++ b/bsdiff
@@ -1 +1 @@
-Subproject commit 1edf9f656850c0c64dae260960fabd8249ea9c60
+Subproject commit b817e9491cf7b8699c8462ef9e2657ca4ccd7667