build broken in compare_sgemm_bgemm.c for ppc64le after a recent change

Seems that commit f95e7b0 breaks build on ppc64le with at least the POWER8 kernel as it hardcodes an `#include <arm_neon.h>`
````
...
compare_sgemm_bgemm.c:31:10: fatal error: arm_neon.h: No such file or directory
   31 | #include <arm_neon.h>
      |          ^~~~~~~~~~~~
compilation terminated.
...
````