Explicitly set ctest command.

Some generators have trouble finding base_test if this project is
included as a subproject. Explicitly setting the test name and
executable command will fix this issue.
diff --git a/src/base/CMakeLists.txt b/src/base/CMakeLists.txt
index 2cd27ae..5a45f85 100644
--- a/src/base/CMakeLists.txt
+++ b/src/base/CMakeLists.txt
@@ -23,5 +23,5 @@
                  test/type_traits_test.cpp
                  test/uint128_test.cpp)
   target_link_libraries(base_test base gmock_main)
-  add_test(base_test base_test)
+  add_test(NAME base_test COMMAND base_test WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
 endif()