replace spurious avx512 requirement with fma check
-/* need a new enough GCC for avx512 support */
-#if (( defined(__GNUC__) && __GNUC__ > 6 && defined(__AVX512CD__)) || (defined(__clang__) && __clang_major__ >= 9))
-
+#if defined(HAVE_FMA3) && defined(HAVE_AVX2)
#define HAVE_DROT_KERNEL 1
#include <immintrin.h>
