Determination of statements that contain matrix multiplication

Add determination of statements that contain, in particular,
matrix multiplications and can be optimized with [1] to try to
get close-to-peak performance. It can be enabled
via polly-pm-based-opts, which is false by default.

Refs:
[1] - http://www.cs.utexas.edu/users/flame/pubs/TOMS-BLIS-Analytical.pdf



Contributed-by: Roman Gareev <gareevroman@gmail.com>
Reviewed-by: Tobias Grosser <tobias@grosser.es>

Differential Revision: http://reviews.llvm.org/D20575

llvm-svn: 271128