Emscripten: Expose FS Module again.

Was lost when moving to MODULARIZE.

Fix #3243

CMakeLists.txt

@@ -1151,6 +1151,7 @@ if(${PLAYER_BUILD_EXECUTABLE} AND ${PLAYER_TARGET_PLATFORM} MATCHES "^SDL(1|2)$"
 			"-sALLOW_MEMORY_GROWTH -sMINIFY_HTML=0 -sMODULARIZE -sEXPORT_NAME=createEasyRpgPlayer \
 			 -sEXIT_RUNTIME --bind --pre-js ${PLAYER_JS_PREJS} --post-js ${PLAYER_JS_POSTJS} \
 			 -sDEFAULT_LIBRARY_FUNCS_TO_INCLUDE=['$autoResumeAudioContext','$dynCall'] \
+			 -sEXPORTED_RUNTIME_METHODS=['FS'] \
 			 -sEXPORTED_FUNCTIONS=_main,_malloc,_free")
 		set_source_files_properties("src/platform/sdl/main.cpp" PROPERTIES
 			OBJECT_DEPENDS "${PLAYER_JS_PREJS};${PLAYER_JS_POSTJS};${PLAYER_JS_SHELL}")