RFR: 8257634: C2: Introduce IncrementalInliningForceCleanup diagnostic flag

[Vladimir Ivanov]

Introduce a diagnostic flag to force cleanup pass after each successful inlining attempt during incremental inlining pass.
It simplifies diagnosing issues caused by dead code (accumulated between cleanup iterations) and provides a way to workaround such issues in production on per-method basis.

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Commit messages:
 - Introduce IncrementalInliningForceCleanup diagnostic flag

Changes: https://git.openjdk.java.net/jdk/pull/1583/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1583&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257634
  Stats: 8 lines in 4 files changed: 7 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1583.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1583/head:pull/1583

PR: https://git.openjdk.java.net/jdk/pull/1583