[foreign-memaccess] Integrated: 8253287: jcheck merge check is too strict

[Maurizio Cimadamore]

The regex for checking merge commits is too strict. This should relax that.

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Commit messages:
 - Fix merge message check in jcheck

Changes: https://git.openjdk.java.net/panama-foreign/pull/332/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=332&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253287
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/332.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/332/head:pull/332

PR: https://git.openjdk.java.net/panama-foreign/pull/332