cstool: support CMake
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 239ba5e..8ae0482 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -388,3 +388,5 @@
             LIBRARY DESTINATION lib
             ARCHIVE DESTINATION lib)
 endif ()
+
+add_subdirectory(cstool)