Need typedef of ssize_t for msc compiler
MODIFY
mrbgems/mruby-io/src/io.c
mrbgems/mruby-io/src/io.c
#if defined(_WIN32) || defined(_WIN64)
#include <winsock.h>
#include <io.h>
+ #include <BaseTsd.h>
#define open _open
#define close _close
#define dup _dup
typedef long fsuseconds_t;
typedef int fmode_t;
typedef int mrb_io_read_write_size;
+ typedef SSIZE_T ssize_t;
#ifndef O_TMPFILE
#define O_TMPFILE O_TEMPORARY

Need typedef of ssize_t for msc compiler