Fix invalid detection of x86_64 platform in `sequtils.c`

pyfastani/_sequtils/sequtils.c

@@ -4,7 +4,7 @@
 #include "sequtils.h"
 #include "complement.h"
 
-#ifdef __X86__ || __X86_64__
+#if defined(__X86__) || defined(__X86_64__)
 #include "cpu_features_x86.h"
 static const X86Features features = GetX86Info().features;
 #endif
@@ -41,6 +41,11 @@ void copy_upper(char* dst, const char* src, size_t len) {
         return neon_copy_upper(dst, src, len);
       else
     #endif
+    #ifdef __aarch64__
+      if (features.neon)
+        return neon_copy_upper(dst, src, len);
+      else
+    #endif
     #if defined(__X86__) || defined(__X86_64__)
       if (features.sse2)
         return sse2_copy_upper(dst, src, len); // fast copying plus upper.