Integrated: Merge lworld

[Vicente Romero]

Merge branch 'lworld' into bworld_merge_lworld
# Conflicts:
#	src/jdk.compiler/share/classes/com/sun/tools/javac/code/Symtab.java
#	src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java
#	test/jdk/valhalla/valuetypes/LayoutIterationTest.java

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Commit messages:
 - Merge branch 'lworld' into bworld_merge_lworld
 - 8372954: [lworld] Remove old implementation of the substitutability test method
 - 8375547: [lworld] Dependency verification fails with assert "Should have been marked for deoptimization"
 - 8376702: [lworld] MemNode::optimize_simple_memory_chain asserts with "invalid node class: Con"
 - 8376059: [lworld] Fix the issues in code generation of StoreLSpecialNode
 - 8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses
 - Merge
 - 8375458: Check legal folder of JDK image for unwanted files
 - 8375978: G1: Convert G1Policy to use Atomic<T>
 - 8375977: G1: Convert JVMCICleaningTask to use Atomic<T>
 - ... and 96 more: https://git.openjdk.org/valhalla/compare/f384d1dd...21cb7beb

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - bworld: https://webrevs.openjdk.org/?repo=valhalla&pr=2027&range=00.0
 - lworld: https://webrevs.openjdk.org/?repo=valhalla&pr=2027&range=00.1

Changes: https://git.openjdk.org/valhalla/pull/2027/files
  Stats: 16334 lines in 429 files changed: 9194 ins; 3825 del; 3315 mod
  Patch: https://git.openjdk.org/valhalla/pull/2027.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2027/head:pull/2027

PR: https://git.openjdk.org/valhalla/pull/2027