core: ignore VTs

Even just walking sysfs for driver and parent devices takes
time for ports we know we'll never use, so take a short-cut
and save some startup time.  This reduces the startup
overhead to some 15%.

src/mm-manager.c

@@ -15,6 +15,7 @@
  */
 
 #include <string.h>
+#include <ctype.h>
 #include <gmodule.h>
 #define G_UDEV_API_IS_SUBJECT_TO_CHANGE
 #include <gudev/gudev.h>
@@ -517,6 +518,10 @@ device_added (MMManager *manager, GUdevDevice *device)
     subsys = g_udev_device_get_subsystem (device);
     name = g_udev_device_get_name (device);
 
+    /* ignore VTs */
+    if (strncmp (name, "tty", 3) == 0 && isdigit (name[3]))
+	return;
+
     if (find_modem_for_port (manager, subsys, name))
         return;