RFR: JDK-8298448: UndefinedBehaviorSanitizer

[Justin King]

Allow building OpenJDK with UBSan. Currently the build fails when optimizing the image due to lots of undefined behavior (it invokes the built JVM). Follow up PRs will either replace the undefined behavior with well defined behavior or suppress errors which are intentional. The goal is to make OpenJDK more well defined and thus more portable across compilers and architectures.

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Commit messages:
 - Remove leftover debugging logic
 - Initial implementation of UBSan

Changes: https://git.openjdk.org/jdk/pull/11604/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11604&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298448
  Stats: 54 lines in 4 files changed: 54 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11604.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11604/head:pull/11604

PR: https://git.openjdk.org/jdk/pull/11604