[jdk13u-dev] RFR: 8272541: Incorrect overflow test in Toom-Cook branch of BigInteger multiplication

[Andrew John Hughes]

Hi all,

This pull request contains a backport of commit [d1aeca11](https://github.com/openjdk/jdk/commit/d1aeca117ccc4334d67b2692ff087a9f8d808a59) from the [openjdk/jdk](https://git.openjdk.java.net/jdk) repository.

The commit being backported was authored by Brian Burkhalter on 27 Aug 2021 and was reviewed by Joe Darcy.
It has already been backported to [jdk17u-dev](https://git.openjdk.java.net/jdk17u-dev/commit/8207e69aa076ba848b8496c4ea0bcbea952aae2a).

This is a clean backport to 11u. As @shipilev notes on the bug, the original code (JDK-8200659) was backported to all active branches in the January 2019 security update, so we should update the test everywhere as well.

Thanks!

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Commit messages:
 - Backport d1aeca117ccc4334d67b2692ff087a9f8d808a59

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/327/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=327&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272541
  Stats: 30 lines in 2 files changed: 18 ins; 3 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/327.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/327/head:pull/327

PR: https://git.openjdk.java.net/jdk13u-dev/pull/327