[clang] [Matrix] Add a row\col major toggle in the clang driver (PR #167628)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

@cofibrant @fhahn  I'll be looking to complete this PR tomorrow morning. If things still need to be addressed I'll be happy to do so via post-commit feedback. 

https://github.com/llvm/llvm-project/pull/167628