[lworld] RFR: 8247686: [lworld] C2 compilation fails with assert(!is_default(*igvn)) failed: default value type allocation

[Tobias Hartmann]

We need to handle dead (default) inline type allocations in ValueTypeNode::Ideal and remove membars in
PhaseMacroExpand::process_users_of_allocation.

I've also fixed a failed merge of JDK-8246453 (see library_call.cpp changes):
https://hg.openjdk.java.net/jdk/jdk/rev/6a4bdf4655ce

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Commit messages:
 - 8247686: [lworld] C2 compilation fails with assert(\!is_default(*igvn)) failed: default value type allocation

Changes: https://git.openjdk.java.net/valhalla/pull/86/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/86/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8247686
  Stats: 40 lines in 3 files changed: 10 ins; 8 del; 22 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/86.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/86/head:pull/86

PR: https://git.openjdk.java.net/valhalla/pull/86