RFR: 8286775: Remove identical per-compiler definitions of unsigned integral types

[David Holmes]

Trivial update to share the common typedef's.

Testing: 
  - Oracle tier 1 - 5 builds
  - GHA (TBD)

Thanks.

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Commit messages:
 - 8286775: Remove identical per-compiler definitions of unsigned integral jtypes

Changes: https://git.openjdk.org/jdk/pull/12136/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12136&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8286775
  Stats: 32 lines in 4 files changed: 8 ins; 24 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12136.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12136/head:pull/12136

PR: https://git.openjdk.org/jdk/pull/12136