Testing split fused l2 knn compilation units (#4514)

Authors:
  - Corey J. Nolet (https://github.com/cjnolet)

Approvers:
  - Dante Gama Dessavre (https://github.com/dantegd)

URL: #4514

cpp/bench/prims/fused_l2_nn.cu

@@ -21,6 +21,7 @@
 #include <raft/handle.hpp>
 #include <raft/linalg/norm.cuh>
 #include <raft/random/rng.hpp>
+#include <raft/spatial/knn/specializations.hpp>
 
 namespace MLCommon {
 namespace Bench {