message: add encoding_rs OOB arithmetic
diff: @@ -320,6 +320,7 @@ Definite bugs found:
  * [TiKV performing an unaligned pointer access](https://github.com/tikv/tikv/issues/7613)
  * [`servo_arc` creating a dangling shared reference](https://github.com/servo/servo/issues/26357)
  * [TiKV constructing out-of-bounds pointers (and overlapping mutable references)](https://github.com/tikv/tikv/pull/7751)
  +* [`encoding_rs` doing out-of-bounds pointer arithmetic](https://github.com/hsivonen/encoding_rs/pull/53)
  Violations of [Stacked Borrows] found that are likely bugs (but Stacked Borrows is currently just an experiment):
  