RFR: JDK-8298448: UndefinedBehaviorSanitizer [v3]

[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.

Justin King has updated the pull request incrementally with one additional commit since the last revision:

  Add comment explaining __ubsan_default_options and UBSAN_OPTIONS
  
  Signed-off-by: Justin King <jcking at google.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11604/files
  - new: https://git.openjdk.org/jdk/pull/11604/files/6f8c8394..e104ec05

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11604&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11604&range=01-02

  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 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