Packet4ul does not have Abs2

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 d61e548..fc525bf 100644
--- a/Eigen/src/Core/arch/AVX/PacketMath.h
+++ b/Eigen/src/Core/arch/AVX/PacketMath.h
@@ -277,6 +277,7 @@
     HasNegate = 0,
     HasSqrt = 0,
     HasMul = 0,
+    HasAbs2 = 0,
     HasCmp = 1,
     HasShift = 1
   };