Use correct output device for Windows prompts.

This ensures that mapping of non-ascii prompts
to the correct code page occurs.

Bug report and original patch from Alexander Law,
reviewed and reworked by Noah Misch.

Backpatch to all live branches.

src/bin/psql/command.c

@@ -1043,6 +1043,17 @@ exec_command(const char *cmd,
 		char	   *fname = psql_scan_slash_option(scan_state,
 												   OT_NORMAL, NULL, true);
 
+#if defined(WIN32) && !defined(__CYGWIN__)
+
+		/*
+		 * XXX This does not work for all terminal environments or for output
+		 * containing non-ASCII characters; see comments in simple_prompt().
+		 */
+#define DEVTTY	"con"
+#else
+#define DEVTTY	"/dev/tty"
+#endif
+
 		expand_tilde(&fname);
 		/* This scrolls off the screen when using /dev/tty */
 		success = saveHistory(fname ? fname : DEVTTY, -1, false, false);