implement wprintf family of functions

this implementation is extremely ugly and inefficient, but it avoids a
good deal of code duplication and bloat. it may be cleaned up later to
eliminate the remaining code duplication and some of the warts, but i
don't really care about its performance.

note that swprintf is not yet implemented.

src/stdio/wprintf.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include <wchar.h>
+
+int wprintf(const wchar_t *fmt, ...)
+{
+	int ret;
+	va_list ap;
+	va_start(ap, fmt);
+	ret = vwprintf(fmt, ap);
+	va_end(ap);
+	return ret;
+}