Fix backwards test for Windows service-ness in pg_ctl.

A thinko in a96761391 caused pg_ctl to get it exactly backwards when
deciding whether to report problems to the Windows eventlog or to stderr.
Per bug #14001 from Manuel Mathar, who also identified the fix.
Like the previous patch, back-patch to all supported branches.

src/bin/pg_ctl/pg_ctl.c

@@ -216,7 +216,7 @@ write_stderr(const char *fmt,...)
 	 * On Win32, we print to stderr if running on a console, or write to
 	 * eventlog if running as a service
 	 */
-	if (!pgwin32_is_service())	/* Running as a service */
+	if (pgwin32_is_service())	/* Running as a service */
 	{
 		char		errbuf[2048];		/* Arbitrary size? */