Add cmake_install_test, cmake_subdir_test

test/cmake_subdir_test/CMakeLists.txt

@@ -0,0 +1,18 @@
+# Copyright 2018, 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(cmake_subdir_test LANGUAGES CXX)
+
+add_subdirectory(../../../static_assert boostorg/static_assert)
+add_subdirectory(../../../config boostorg/config)
+
+add_executable(main main.cpp)
+target_link_libraries(main Boost::static_assert)
+
+enable_testing()
+add_test(NAME main COMMAND main)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)