RFR: 8254360: Re-examine use of CodeBuffer::verify_section_allocation

[Claes Redestad]

- In release builds, only call `verify_section_allocation` in `~CodeBuffer`. This reduce overhead, while retaining most of the verification promises in product builds.
- Minor touch-ups the implementation of `verify_section_allocation`: Use is_aligned. Add a `disjoint` predicate. Only compare two sections once per verification. Remove some redundant checks.

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Commit messages:
 - Merge branch 'master' into verify_section_alloc
 - Merge branch 'master' into verify_section_alloc
 - Ptrs schmtrs
 - Factor out disjoint property, avoid redundant checks (disjointedness is symmetric)
 - 8254360: Re-examine use of CodeBuffer::verify_section_allocation

Changes: https://git.openjdk.java.net/jdk/pull/1421/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1421&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254360
  Stats: 23 lines in 2 files changed: 7 ins; 2 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1421.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1421/head:pull/1421

PR: https://git.openjdk.java.net/jdk/pull/1421