Many tests that were in test/Analysis/CostModel were actually
loop vectoriser tests. I've moved them as follows:
Analysis/CostModel/X86 -> Transforms/LoopVectorize/X86/CostModel
Analysis/CostModel/AArch64/arith-fp-frem.ll ->
Transforms/LoopVectorize/AArch64/arith-fp-frem-costs.ll