RFR: 8257229: gtest death tests fail with unrecognized stderr output

[Ioi Lam]

The regexp used by the TEST_VM_ASSERT_MSG macro is too restrictive. It shouldn't require that "assert failed" to be the very beginning of the VM output. Note that the other macro, TEST_VM_ASSERT, does not have the "^" in its regexp.

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Commit messages:
 - 8257229: gtest death tests fail with unrecognized stderr output

Changes: https://git.openjdk.java.net/jdk/pull/1748/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1748&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257229
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1748.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1748/head:pull/1748

PR: https://git.openjdk.java.net/jdk/pull/1748