[jdk11u-dev] RFR: 8215759: [test] java/math/BigInteger/ModPow.java can throw an ArithmeticException

[Goetz Lindenmaier]

I backport this for parity with 11.0.19-oracle.

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Commit messages:
 - Backport fedf0767fce4d2df42df6988bcbf12f249e7fa26

Changes: https://git.openjdk.org/jdk11u-dev/pull/1632/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1632&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8215759
  Stats: 12 lines in 1 file changed: 7 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1632.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1632/head:pull/1632

PR: https://git.openjdk.org/jdk11u-dev/pull/1632