crc32-replace-self-test.diff
Replaced the unit test provided in crc32.c, which doesn't have a
makefile and doesn't compile with current headers, with a simpler
self test routine that also gives a measure of performance and
runs at module init time. The self test option can be enabled
through a configuration option CONFIG_CRC32_SELFTEST.

The test stresses the pre and post loops and is thus not very
realistic since actual uses will likely have addresses and lengths
that are at least 4 byte aligned. However, the main loop is long
enough so that the performance is dominated by that loop.

The expected values for crc32_le and crc32_be were generated
with the original version of crc32.c using CRC_BITS_LE = 8 and
CRC_BITS_BE = 8. These values were then used to check all the
values of the BITS parameters in both the original and new versions.

The performance results show some variability from run to run
in spite of attempts to both warm the cache and reduce the amount
of OS noise by limiting interrutps during the test. To get comparable
results and to analyse options wrt performance the best time
reported over a small sample of runs has been taken.

Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>