RFR: 8377172: Change datatype of CodeEntryAlignment to uint

[Leo Korinth]

The main idea of this change is to remove an implicitly narrowing conversion to int from intx (`int code_alignment()`).

CodeEntryAlignment is constrained to not be bigger than CodeCacheSegmentSize that is itself constrained to be in the range(1, 1024). The data type should really be a uint16_t as its allowed range is [16-1024], but we have no such support for VM flags. uint will do, and will simplify the code greatly (five less casts, six if we count the implicit narrowing cast).

Also add explicit range on the flag.

This change is inspired by my change 8376892: Allow conversion warnings in subsets of the code base.

Completed test tier 1-3.

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Commit messages:
 - OptoLoopAlignment and InteriorEntryAlignment should be unsigned.
 - 8377172: Change datatype of CodeEntryAlignment to uint

Changes: https://git.openjdk.org/jdk/pull/29637/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29637&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377172
  Stats: 36 lines in 16 files changed: 3 ins; 2 del; 31 mod
  Patch: https://git.openjdk.org/jdk/pull/29637.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29637/head:pull/29637

PR: https://git.openjdk.org/jdk/pull/29637