Fix error: unused parameter 'tmp' [-Werror,-Wunused-parameter] on clang/32-bit arm

Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h

diff --git a/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h b/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h
index 5dc5ef8..c892d39 100644
--- a/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h
+++ b/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h
@@ -26,7 +26,7 @@
 
   template <typename LaneIdType>
   EIGEN_STRONG_INLINE void madd(const Packet4f& a, const Packet4f& b,
-                                Packet4f& c, Packet4f& tmp,
+                                Packet4f& c, Packet4f&,
                                 const LaneIdType&) const {
     acc(a, b, c);
   }