Fixed cmake warning.

There is no CMakeLists.txt in tests and we don't build something
in the root CMakeLists.txt.

CMakeLists.txt

@@ -61,10 +61,6 @@ configure_file(config.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config.h)
 add_subdirectory(doc)
 add_subdirectory(include)
 add_subdirectory(libssh)
-add_subdirectory(tests)
-
-# build samples
-include_directories(${CMAKE_SOURCE_DIR}/include)
 
 # pkg-config file
 configure_file(libssh.pc.cmake ${CMAKE_CURRENT_BINARY_DIR}/libssh.pc)