Add .cpubench tag to ProtocolDispatch2

Author: atrick

benchmark/single-source/ProtocolDispatch2.swift

@@ -19,7 +19,7 @@ import TestsUtils
 public let ProtocolDispatch2 = BenchmarkInfo(
   name: "ProtocolDispatch2",
   runFunction: run_ProtocolDispatch2,
-  tags: [.validation, .abstraction])
+  tags: [.validation, .abstraction, .cpubench])
 
 protocol Pingable { func ping() -> Int;  func pong() -> Int}