Cherry pick fix for usrsctp UAF bug to M86.

The commit being cherry picked is:
https://github.com/sctplab/usrsctp/commit/ffed0925f27d404173c1e3e750d818f432d2c019

TBR=hta@chromium.org

Bug: chromium:1124659
Change-Id: I229c8a01fd051b1dfe499a609f72484ce7611af3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424803
Reviewed-by: Krishna Govind <govind@chromium.org>
Reviewed-by: Prudhvi Kumar Bommana <pbommana@google.com>
Commit-Queue: Krishna Govind <govind@chromium.org>
Commit-Queue: Taylor <deadbeef@chromium.org>
Cr-Commit-Position: refs/branch-heads/4240@{#941}
Cr-Branched-From: f297677702651916bbf65e59c0d4bbd4ce57d1ee-refs/heads/master@{#800218}
diff --git a/DEPS b/DEPS
index bfc73978..bac699fa 100644
--- a/DEPS
+++ b/DEPS
@@ -1427,7 +1427,7 @@
   },
 
   'src/third_party/usrsctp/usrsctplib':
-    Var('chromium_git') + '/external/github.com/sctplab/usrsctp' + '@' + 'a8c51df76caae94254b1e59999405f739467490e',
+    Var('chromium_git') + '/external/github.com/sctplab/usrsctp' + '@' + '6b40d1884165cfde314241ea8f6d62c24a726ae0',
 
   'src/third_party/vulkan_memory_allocator':
     Var('chromium_git') + '/external/github.com/GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator.git' + '@' + '6c656df63da5995a932aafd45b32af1974e497d9',
diff --git a/third_party/usrsctp/README.chromium b/third_party/usrsctp/README.chromium
index 18ebfe0d..9491abe 100644
--- a/third_party/usrsctp/README.chromium
+++ b/third_party/usrsctp/README.chromium
@@ -18,3 +18,10 @@
    draft-stewart-prsctp-00.txt
    draft-stewart-tsvwg-sctpipv6-00.txt
    draft-iyengar-sctp-cacc-00.txt
+
+Local Modifications:
+The following commits have been cherry picked on top of the base revision
+listed above:
+858d2f73019f73bd2c1691bab75c2022640b82e7
+e1dd9bea4f438abf4d4c3b658f1db8f013157184
+ffed0925f27d404173c1e3e750d818f432d2c019