Add WITH_SDL

src/conio/CMakeLists.txt

@@ -101,6 +101,8 @@ endif()
 
 if(SDL2_INCLUDE_DIRS)
 	target_include_directories(ciolib PUBLIC ${SDL2_INCLUDE_DIRS})
+	set(WITH_SDL TRUE)
+	target_compile_definitions(ciolib PUBLIC WITH_SDL)
 endif()
 
 if(NOT WIN32)