main: suppress creation of consol window on MS Windows

* Rust applications on Windows always open a new console window
  if started by double-clicking on the executable.
* since rust 1.18 the the macro suppresses this behaviour

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

advotracker/src/main.rs

@@ -7,6 +7,8 @@
 
 //#[macro_use]
 //extern crate lazy_static;
+// suppress creation of a new console window on window
+#![windows_subsystem = "windows"]
 
 //use chrono::{Local, DateTime};
 use locales::t;
@@ -54,6 +56,14 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     use tracing_subscriber::fmt;
     use viperus::Viperus;
 
+    let machine_kind = if cfg!(unix) {
+	"unix"
+    } else if cfg!(windows) {
+	"windows"
+    } else {
+	"unknown/unsupported"
+    };
+
     //use advotracker::callbacks::policy_check::is_valid;
     //use advotracker::data::structures::{PolicyCode, PolicyDataList, PolicyList};
     // WIP: can't push pointer by value to widget, call import in widget callback for now