Implement basic canonical mode for Windows

The `cat` command now works properly, when run by itself on the bash
command prompt. It's working beautifully so far, and is only missing
a few keystrokes for clearing words and lines. Definitely works more
well than the one that ships with WIN32 :-)

libc/stdio/fmt.c

@@ -1048,7 +1048,7 @@ int __fmt(void *fn, void *arg, const char *format, va_list va) {
         // undocumented %r specifier
         // used for good carriage return
         // helps integrate loggers with repls
-        if (!__replstderr) {
+        if (!__ttyconf.replstderr) {
           break;
         } else {
           p = "\r\e[K";