RFR: 8130687: aarch64: add support for hardware crc32c

[Edward Nevill]

Hi,

http://cr.openjdk.java.net/~enevill/8130687/webrev/hotspot.changeset

adds support for crc32c on aarch64. This has previously been added for Sparc (see https://bugs.openjdk.java.net/browse/JDK-8073583)

Performance measurements shows the throughput goes from ~620MB/s to 2938 MB/s == approx 4.7x performance improvement.

Tested before and after with jtreg hotspot. In both cases

Test results: passed: 867; failed: 3; error: 7

Please review.

Thanks,
Ed.