AVX: guard Packet4l definition

Eigen/src/Core/arch/AVX/PacketMath.h

diff --git a/Eigen/src/Core/arch/AVX/PacketMath.h b/Eigen/src/Core/arch/AVX/PacketMath.h
index 4a0c72e..ebea1dc 100644
--- a/Eigen/src/Core/arch/AVX/PacketMath.h
+++ b/Eigen/src/Core/arch/AVX/PacketMath.h
@@ -330,7 +330,9 @@
 struct unpacket_traits<Packet4d> {
   typedef double type;
   typedef Packet2d half;
+#ifdef EIGEN_VECTORIZE_AVX2
   typedef Packet4l integer_packet;
+#endif
   enum {
     size = 4,
     alignment = Aligned32,