In the command-line shell, make sure stderr is unbuffered so that it

automatically flushes.  This has always been the case already for unix and
on Windows when the output is a console, but apparently was not the case
on Windows when the output was a pipe.

FossilOrigin-Name: 2a9ea9b4a7d6904efb2112e32efe84123dfa75d7

src/shell.c

@@ -4195,6 +4195,7 @@ int main(int argc, char **argv){
   }
 #endif
   setBinaryMode(stdin);
+  setvbuf(stderr, 0, _IONBF, 0); /* Make sure stderr is unbuffered */
   Argv0 = argv[0];
   main_init(&data);
   stdin_is_interactive = isatty(0);