misc/py-llama-cpp-python: fix build on powerpc64*

/wrkdirs/usr/ports/misc/py-llama-cpp-python/work-py311/llama-cpp-python-0.3.2/vendor/llama.cpp/ggml/src/ggml-cpu/llamafile/sgemm.cpp:1659:1: error: unknown type name '_Bool'
1659 | bool llamafile_sgemm(int64_t m, int64_t n, int64_t k, const void *A, int64_t lda, const void *B, int64_t ldb, void *C,

| ^

/wrkdirs/usr/ports/misc/py-llama-cpp-python/work-py311/llama-cpp-python-0.3.2/vendor/llama.cpp/ggml/src/ggml-cpu/./ggml-cpu-impl.h:323:14: note: expanded from macro 'bool'

323 | #define bool _Bool
    |              ^

4 warnings and 1 error generated.