RFR: 8255026: C2: Miscellaneous cleanups in Compile and PhaseIdealLoop code

[Vladimir Ivanov]

Miscellaneous cleanups in Compile and PhaseIdealLoop code.

Compile:

- inline node lists

- remove empty Compile::register_library_intrinsics()

- introduce `Compile::remove_useless_nodes(GrowableArray<Node*>& node_list, Unique_Node_List& useful)`


PhaseIdealLoop:

- unify logging and IGVN logic

- refactor logging code

Testing: tier1 - tier5

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Commit messages:
 - 8255026: C2: Miscellaneous cleanups in Compile and PhaseIdealLoop code

Changes: https://git.openjdk.java.net/jdk/pull/749/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=749&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255026
  Stats: 189 lines in 6 files changed: 33 ins; 72 del; 84 mod
  Patch: https://git.openjdk.java.net/jdk/pull/749.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/749/head:pull/749

PR: https://git.openjdk.java.net/jdk/pull/749