[jdk11u-dev] RFR: 8335803: SunJCE cipher throws NPE for un-extractable RSA keys

[Alexey Bakhtin]

Please review the fix for NPE in RSAPrivateCrtKeyImpl if a custom un-extractable key is provided.

This is a behavioral regression since [JDK-8023980](https://bugs.openjdk.org/browse/JDK-8023980)

Related JTREG tests passed

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Commit messages:
 - 8335803: SunJCE cipher throws NPE for un-extractable RSA keys

Changes: https://git.openjdk.org/jdk11u-dev/pull/2837/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2837&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335803
  Stats: 85 lines in 2 files changed: 81 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2837.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2837/head:pull/2837

PR: https://git.openjdk.org/jdk11u-dev/pull/2837