RFR: 8297382: Test fails to compile after JDK-8288047

[Tobias Hartmann]

[JDK-8288047](https://bugs.openjdk.org/browse/JDK-8288047) added `long[] getLimbs()` to `src/java.base/share/classes/sun/security/util/math/IntegerModuloP.java` but forgot to override that method in test implementation `test/jdk/sun/security/util/math/BigIntegerModuloP.java`.

Thanks,
Tobias

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Commit messages:
 - 8297382: Test fails to compile after JDK-8288047

Changes: https://git.openjdk.org/jdk/pull/11282/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11282&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297382
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11282.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11282/head:pull/11282

PR: https://git.openjdk.org/jdk/pull/11282