CMake: fix CMAKE_MODULE_PATH extension declaration

Signed-off-by: Roman Ondráček <mail@romanondracek.cz>

Author: Roman3349

CMakeLists.txt

@@ -26,7 +26,7 @@ message(STATUS "CMake version: " ${CMAKE_VERSION})
 message(STATUS "CMake system name: " ${CMAKE_SYSTEM_NAME})
 
 set(CMAKE_SCRIPTS "${PROJECT_SOURCE_DIR}/cmake")
-set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
+list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
 
 ## Project Version
 ## Previously we read in the version from these files, but now we use the