RFR: 8272472: StackGuardPages test doesn't build with glibc 2.34

[David Holmes]

Please review this simple test fix to address an issue that will prevent this test source from building on more recent Linux distributions with Glibc 2.34. When building under _GNU_SOURCE the value of SIGSTKSZ is no longer a constant and so cannot be used in an array declaration. The simple fix is to malloc the array instead.

Testing: local & mach5 tiers 1-3

Thanks,
David

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Commit messages:
 - 8272472: StackGuardPages test doesn't build with glibc 2.34

Changes: https://git.openjdk.java.net/jdk/pull/5200/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5200&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272472
  Stats: 11 lines in 1 file changed: 9 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5200.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5200/head:pull/5200

PR: https://git.openjdk.java.net/jdk/pull/5200