[llvm] [NFC][PowerPC] Pre-commit testcases for locking down the xxsel instructions for ternary(A, X, eqv(B, C)), ternary(A, X, not(C)), ternary(A, X, not(B)), ternary(A, X, nand(B, C)) and ternary(A, X, nor(B, C)) patterns (PR #158091)

[Tony Varghese via llvm-commits]

https://github.com/tonykuttai edited https://github.com/llvm/llvm-project/pull/158091