This patch adds a -matrix-default-layout option which can be used to
set the default matrix layout to row-major or column-major (default).
The initial patch updates codegen for loads, stores, binary operators
and matrix multiply.
Reviewers: anemet, Gerolf, andrew.w.kaylor, LuoYuanke
Reviewed By: anemet
Differential Revision: https://reviews.llvm.org/D76325
Florian Hahn