implement [v]swprintf

src/stdio/swprintf.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include <wchar.h>
+
+int swprintf(wchar_t *s, size_t n, const wchar_t *fmt, ...)
+{
+	int ret;
+	va_list ap;
+	va_start(ap, fmt);
+	ret = vswprintf(s, n, fmt, ap);
+	va_end(ap);
+	return ret;
+}
+