Move tests inclusion in a test CMakeList

The root CMakeList was including every test directories
directly, although it should be kept simple.

Move the inclusions to a dedicated CMakeList in test.

Signed-off-by: Kevin Rocard <kevin.rocard@intel.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 37a9ffa..fbff0d9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -65,11 +65,7 @@
                  PYTHONPATH=${CMAKE_BINARY_DIR}/bindings/python:$ENV{PYTHONPATH})
 endfunction()
 
-add_subdirectory(test/test-platform)
-add_subdirectory(test/test-fixed-point-parameter)
-add_subdirectory(test/tokenizer)
-add_subdirectory(test/functional-tests)
-add_subdirectory(test/test-subsystem)
+add_subdirectory(test)
 
 option(BASH_COMPLETION "Install bash completion configuration" ON)
 if (BASH_COMPLETION)