RFR: JDK-8300069: Left shift of negative value in share/adlc/dict2.cpp [v2]

[Justin King]

> Refactor `hashstr` to use unsigned integrals to avoid undefined behavior.

Justin King has updated the pull request incrementally with two additional commits since the last revision:

 - Revert share/adlc/dict2.cpp changes
   
   Signed-off-by: Justin King <jcking at google.com>
 - Silence undefined behavior checking for left hand side of shift
   
   Signed-off-by: Justin King <jcking at google.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/11977/files
  - new: https://git.openjdk.org/jdk/pull/11977/files/2cc7a432..260b82ed

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11977&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11977&range=00-01

  Stats: 7 lines in 2 files changed: 1 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/11977.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11977/head:pull/11977

PR: https://git.openjdk.org/jdk/pull/11977