Add method to TargetInfo to get CPU cache line size
This patch adds a virtual method getCPUCacheLineSize() to TargetInfo. Currently, I've only implemented the method in X86TargetInfo. It's extremely important that each CPU's cache line size correct (e.g., we can't just define it as 64 across the board) so, it has been a little slow getting to this point.
I'll work on the ARM CPUs next, but that will probably come later in a different patch.
Differential Revision: https://reviews.llvm.org/D74918