MMU: Move the lookup tables to the heap in 64-bit builds and free them on exit in 32-bit builds, prevents memory leaks.

src/86box.c

@@ -1656,6 +1656,10 @@ pc_close(UNUSED(thread_t *ptr))
     scsi_disk_close();
 
     gdbstub_close();
+
+#if (!(defined __amd64__ || defined _M_X64 || defined __aarch64__ || defined _M_ARM64))
+    mem_free();
+#endif
 }
 
 #ifdef __APPLE__