Fix navy compilation issue (facebook#171)

Summary:
EnginePair.cpp file was not added to CMakeLists.txt which led to linking failure.

Pull Request resolved: facebook#171

Reviewed By: therealgymmy

Differential Revision: D40952556

Pulled By: jiayuebao

fbshipit-source-id: 5a8931d4899c73af0555f5be5659f2b501d9941a

Author: igchor

cachelib/navy/CMakeLists.txt

@@ -35,6 +35,7 @@ add_library (cachelib_navy
   common/SizeDistribution.cpp
   common/Types.cpp
   driver/Driver.cpp
+  engine/EnginePair.cpp
   Factory.cpp
   scheduler/ThreadPoolJobScheduler.cpp
   scheduler/ThreadPoolJobQueue.cpp