RFR: JDK-8312617: SIGSEGV in ConnectionGraph::verify_ram_nodes [v2]

[Cesar Soares Lucas]

> - Return early from `verify_ram_nodes` if compilation is already failing.
> - Add back check for `failing()` after `eliminate_macro_nodes()`.
> - Print additional diagnostic information when an unexpected user of RAM is encountered.
> 
> Tested with tier1-3 on Linux x64.

Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:

  Refactoring use of flags.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15048/files
  - new: https://git.openjdk.org/jdk/pull/15048/files/d4ca4f2e..b55cba76

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15048&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15048&range=00-01

  Stats: 9 lines in 2 files changed: 1 ins; 3 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/15048.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15048/head:pull/15048

PR: https://git.openjdk.org/jdk/pull/15048