[jdk11u] RFR: 8299658: C1 compilation crashes in LinearScan::resolve_exception_edge

[Martin Doerr]

Clean backport of [JDK-8299658](https://bugs.openjdk.org/browse/JDK-8299658) + replacement of `nullptr` which is not allowed in 11u.

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Commit messages:
 - Replace nullptr by NULL.
 - Backport cf2d33ca2ee08c61596ab10b7602500a6931fa31

Changes: https://git.openjdk.org/jdk11u/pull/82/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u&pr=82&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299658
  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u/pull/82.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u.git pull/82/head:pull/82

PR: https://git.openjdk.org/jdk11u/pull/82