call: Add unknown state

This is the default fallback state and is useful f.e. in the oFono plugin
if the GDBOVoiceCall doesn't provide a state in its' properties.

src/calls-call.c

@@ -200,7 +200,7 @@ calls_call_class_init (CallsCallClass *klass)
                        "State",
                        "The current state of the call",
                        CALLS_TYPE_CALL_STATE,
-                       CALLS_CALL_STATE_ACTIVE,
+                       CALLS_CALL_STATE_UNKNOWN,
                        G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
 
   properties[PROP_PROTOCOL] =

src/calls-call.h

@@ -37,7 +37,8 @@ G_DECLARE_DERIVABLE_TYPE (CallsCall, calls_call, CALLS, CALL, GObject)
 
 typedef enum
 {
-  CALLS_CALL_STATE_ACTIVE = 1,
+  CALLS_CALL_STATE_UNKNOWN = 0,
+  CALLS_CALL_STATE_ACTIVE,
   CALLS_CALL_STATE_HELD,
   CALLS_CALL_STATE_DIALING,
   CALLS_CALL_STATE_ALERTING,