RFR: 8277361: java/nio/channels/Channels/ReadXBytes.java fails with OOM error

[Brian Burkhalter]

This request would increase the amount of heap memory that the test can use, and decrease execution time by not writing the entirety of test files.

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Commit messages:
 - 8277361: java/nio/channels/Channels/ReadXBytes.java fails with OOM error

Changes: https://git.openjdk.java.net/jdk/pull/6732/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6732&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277361
  Stats: 39 lines in 1 file changed: 23 ins; 2 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6732.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6732/head:pull/6732

PR: https://git.openjdk.java.net/jdk/pull/6732