erasure-code: workunit to check for encoding regression

Clone the archive of encoded objects and decode all archived objects, up
to and including the current ceph version.

http://tracker.ceph.com/issues/9420 Refs: #9420

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
erasure-code: s/alignement/alignment/ typos in jerasure

The jerasure-per-chunk-alignment prameter was mispelled and while
useable that would lead to confusion.

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
erasure-code: Makefile.am cosmetics

Cluster benchmark related lines together.

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
erasure-code: restore jerasure BlaumRoth default w

Changing from W=7 to W=6 by default for the BlaumRoth technique is
correct but introduces a regression. The content that was encoded with
the previous version cannot be read again. Although the prime(w+1)
constraint was not obeyed by W=7, the encoded content was useable and
should keep being readable.

The W=7 remains the default for backward compatibility and an exception
to the prime(w+1) check.

http://tracker.ceph.com/issues/9572 Fixes: #9572

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
erasure-code: add corpus verification to make check

Signed-off-by: Loic Dachary <loic-201408@dachary.org>