Fix lowering of pow() in D3D12Compute when the base is provably positive#8813

shoaibkamil wants to merge 2 commits intomainhalide/Halide:mainfrom

shoaibkamil/d3d12compute_pow_positive_basehalide/Halide:shoaibkamil/d3d12compute_pow_positive_baseCopy head branch name to clipboard