RFR: 8239497: SEGV in EdgeUtils::field_name_symbol(Edge const&)

[John Spurling]

Hi,

Please review this backport of JDK-8239497.

Bug: https://bugs.openjdk.java.net/browse/JDK-8239497
Original change: https://hg.openjdk.java.net/jdk/jdk/rev/743c9071c317
Web rev: https://cr.openjdk.java.net/~tonyp/8239497/webrev.0/

As noted in the JIRA issue, we (Twitter) experienced a test failure in
jdk/jfr/startupargs/TestOldObjectQueueSize.java when running Graal. We
have tested this patch in a loop for four days and not experienced a
failure. The patch to 15 did not apply cleanly to 11; this patch is
the one posted by Markus Grönlund in JIRA.

Thanks,
john