math/onednn: fix build on powerpc64
/wrkdirs/usr/ports/math/onednn/work/oneDNN-3.12/src/cpu/ppc64/ppc64_gemm_reorder.cpp:32:25: error: use of 'long long' with '__vector' requires VSX support (available on POWER7 or later) to be enabled
32 | typedef __vector signed long long vec_i64 __attribute__((aligned(8))); | ^
1 error generated.