RFR: 8206179: com/sun/management/OperatingSystemMXBean/GetCommittedVirtualMemorySize.java fails with Committed virtual memory size illegal value

[Daniil Titov]

Please review the change that fixes the failure of the test.

The test assumes that the amount of the virtual memory committed to the process could not
be greater than the total of the RAM and the swap size the machine has, however, it is not
correct if, for example, the process uses a memory-mapped file.

That results in the test failure on the machines where the total of the RAM and the size of the swap
file is less than the memory committed to the test process.

Webrev: https://cr.openjdk.java.net/~dtitov/8206179/webrev.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8206179

Thanks,
--Daniil