* ggml-cpu : rework weak alias on apple targets * fix powerpc detection * fix ppc detection * fix powerpc detection on darwin
* ggml : riscv: add xtheadvector support * ggml : clean up some macro usage
* ggml : add 128-bit RVV support * ggml : revert to old RVV 256+ q2_K, q3_K, q4_K, q6_K impl * remove trailing whitespaces * restructure vector length selection code