Alias _vsnprintf as vsnprintf.

include/msvcrt/stdio.h

diff --git a/include/msvcrt/stdio.h b/include/msvcrt/stdio.h
index 07492e7..fa39c82 100644
--- a/include/msvcrt/stdio.h
+++ b/include/msvcrt/stdio.h
@@ -269,6 +269,7 @@
 static inline int unlink(const char* path) { return _unlink(path); }
 #define MSVCRT_UNLINK_DEFINED
 #endif
+static inline int vsnprintf(char *buffer, size_t size, const char *format, va_list args) { return _vsnprintf(buffer,size,format,args); }
 
 static inline MSVCRT(wint_t) fgetwchar(void) { return _fgetwchar(); }
 static inline MSVCRT(wint_t) fputwchar(MSVCRT(wint_t) wc) { return _fputwchar(wc); }