Don't install googletest and googlemock
diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index ba5207f..e710ddd 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -40,7 +40,7 @@
           "Use shared (DLL) run-time lib even when Google Test is built as static lib."
           ON)
       endif()
-      add_subdirectory(${GMOCK_DIR})
+      add_subdirectory(${GMOCK_DIR} EXCLUDE_FROM_ALL)
     endif()
   endif()
   if (TARGET gmock)