vppinfra: fallback to builtin memcpy if vector code is not enabled

Type: fix
Fixes: 56f54af
Change-Id: I678ff3622640c911eefb57a9288ef95ed859eeb9
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vppinfra/memcpy_x86_64.h b/src/vppinfra/memcpy_x86_64.h
index 9662ab4..e206c69 100644
--- a/src/vppinfra/memcpy_x86_64.h
+++ b/src/vppinfra/memcpy_x86_64.h
@@ -597,10 +597,9 @@
     }
   return dst;
 #else
-#error "SSE/AVX2/AVX512 must be enabled"
-#endif
-
+  __builtin_memcpy (dst, src, n);
   return dst;
+#endif
 }
 
 /* clang-format off */