Fix compile error on Mac

Adds `#include <limits.h>` for PATH_MAX.

src/hll/SengokuRanceFont.c

@@ -17,6 +17,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <dirent.h>
+#include <limits.h>
 
 #include "system4.h"
 #include "system4/fnl.h"

src/system4.c

@@ -22,6 +22,7 @@
 #include <ctype.h>
 #include <signal.h>
 #include <getopt.h>
+#include <limits.h>
 
 #include "system4.h"
 #include "system4/ain.h"