RFR: 8253583: java/util/StringJoiner tests failing on 32-bit VMs after JDK-8246697

[Aleksey Shipilev]

JDK-8246697 added -Xmx4g to test configurations. 32-bit VMs cannot do it. @requires tests the OS RAM size, but you can
easily have the x86_32 host with more than 4G ram, yet JVM would fail to acquire that heap size. Need to check for
bitness explicitly.

Testing:
  - [x] java/util/StringJoiner on x86_64 (still run)
  - [x] java/util/StringJoiner on x86_32 (skipped now)

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Commit messages:
 - 8253583: java/util/StringJoiner tests failing on 32-bit VMs after JDK-8246697

Changes: https://git.openjdk.java.net/jdk/pull/331/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=331&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253583
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/331.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/331/head:pull/331

PR: https://git.openjdk.java.net/jdk/pull/331