LU-11597 tests: skip sanityn tests for PPC

LU-11597 tests: skip sanityn tests for PPC

Several sanityn test suite tests fail consistenly when
testing PPC clients.  These tests should be skipped,
added to the ALWAYS_EXCEPT list, until the failures are
understood and fixed.

Tests to skip in sanityn are
16a (LU-11597)
71a (LU-11787)

Test-Parameters: trivial clientarch=ppc64 testlist=sanityn
Signed-off-by: James Nunez <jnunez@whamcloud.com>
Change-Id: I39cc9d22e8a47eb8ef59ce8d30e1b6e9aa616a9a
Reviewed-on: https://review.whamcloud.com/37561
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Wei Liu <sarah@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>