LU-5090 tests: disable MPI tests for Phi build

LU-5090 tests: disable MPI tests for Phi build

MPI tests are not supported for Phi build. So, disable them.
Fix configure messages and caching result of check.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I1fab50500883e6d155c8f324a98bed01e5d96397
Reviewed-on: http://review.whamcloud.com/10508
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>