Modernize code

Can compile with arm-none-eabi-gcc 8.3.0
gbafix correctly handles ELF input

src/mauville_old_man.c

@@ -33,7 +33,7 @@ static void Task_BardSong(u8 taskId);
 static void StorytellerSetup(void);
 static void Storyteller_ResetFlag(void);
 
-IWRAM_DATA u8 sSelectedStory;
+static u8 sSelectedStory;
 
 struct BardSong gBardSong;