This change improves the performance of crc32 for ppc64le by using
vpmsum and other vector instructions in the algorithm.

The testcase was updated to test more sizes.

Fixes #19570

BenchmarkCRC32/poly=IEEE/size=15/align=0-8             90.5          81.8          -9.61%
BenchmarkCRC32/poly=IEEE/size=15/align=1-8             89.7          81.7          -8.92%
BenchmarkCRC32/poly=IEEE/size=40/align=0-8             93.2          61.1          -34.44%
BenchmarkCRC32/poly=IEEE/size=40/align=1-8             92.8          60.9          -34.38%
BenchmarkCRC32/poly=IEEE/size=512/align=0-8            501           55.8          -88.86%
BenchmarkCRC32/poly=IEEE/size=512/align=1-8            502           132           -73.71%
BenchmarkCRC32/poly=IEEE/size=1kB/align=0-8            947           69.9          -92.62%
BenchmarkCRC32/poly=IEEE/size=1kB/align=1-8            946           144           -84.78%
BenchmarkCRC32/poly=IEEE/size=4kB/align=0-8            3602          186           -94.84%
BenchmarkCRC32/poly=IEEE/size=4kB/align=1-8            3603          263           -92.70%
BenchmarkCRC32/poly=IEEE/size=32kB/align=0-8           28404         1338          -95.29%
BenchmarkCRC32/poly=IEEE/size=32kB/align=1-8           28856         1405          -95.13%
BenchmarkCRC32/poly=Castagnoli/size=15/align=0-8       89.7          81.8          -8.81%
BenchmarkCRC32/poly=Castagnoli/size=15/align=1-8       89.8          81.9          -8.80%
BenchmarkCRC32/poly=Castagnoli/size=40/align=0-8       93.8          61.4          -34.54%
BenchmarkCRC32/poly=Castagnoli/size=40/align=1-8       94.3          61.3          -34.99%
BenchmarkCRC32/poly=Castagnoli/size=512/align=0-8      503           56.4          -88.79%
BenchmarkCRC32/poly=Castagnoli/size=512/align=1-8      502           132           -73.71%
BenchmarkCRC32/poly=Castagnoli/size=1kB/align=0-8      941           70.2          -92.54%
BenchmarkCRC32/poly=Castagnoli/size=1kB/align=1-8      943           145           -84.62%
BenchmarkCRC32/poly=Castagnoli/size=4kB/align=0-8      3588          186           -94.82%
BenchmarkCRC32/poly=Castagnoli/size=4kB/align=1-8      3595          264           -92.66%
BenchmarkCRC32/poly=Castagnoli/size=32kB/align=0-8     28266         1323          -95.32%
BenchmarkCRC32/poly=Castagnoli/size=32kB/align=1-8     28344         1404          -95.05%

Change-Id: Ic4d8274c66e0e87bfba5f609f508a3877aee6bb5
Reviewed-on: https://go-review.googlesource.com/38184Reviewed-by: David Chase <drchase@google.com>