cmake: append to CMAKE_MODULE_PATH instead of overwriting
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 30a224c..59ec6bf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,7 +68,8 @@ include(CMakeDependentOption)
include(CMakePushCheckState)
include(FindPkgConfig)
include(GNUInstallDirs)
-set(CMAKE_MODULE_PATH "${SDL2_SOURCE_DIR}/cmake")
+
+list(APPEND CMAKE_MODULE_PATH "${SDL2_SOURCE_DIR}/cmake")
include(${SDL2_SOURCE_DIR}/cmake/macros.cmake)
include(${SDL2_SOURCE_DIR}/cmake/sdlchecks.cmake)