Fix old-style warnings all over the codebase

As caught by compiling with `-Wold-style-definition` and `-Wstrict-prototypes`.

src/calls-contacts-box.c

@@ -212,7 +212,7 @@ calls_contacts_box_init (CallsContactsBox *self)
 
 
 GtkWidget *
-calls_contacts_box_new ()
+calls_contacts_box_new (void)
 {
   return g_object_new (CALLS_TYPE_CONTACTS_BOX, NULL);
 }

src/calls-credentials.c

@@ -298,7 +298,7 @@ calls_credentials_init (CallsCredentials *self)
 
 
 CallsCredentials *
-calls_credentials_new ()
+calls_credentials_new (void)
 {
   return g_object_new (CALLS_TYPE_CREDENTIALS, NULL);
 }

src/calls-credentials.h

@@ -33,7 +33,7 @@ G_BEGIN_DECLS
 G_DECLARE_FINAL_TYPE (CallsCredentials, calls_credentials, CALLS, CREDENTIALS, GObject);
 
 
-CallsCredentials       *calls_credentials_new                     ();
+CallsCredentials       *calls_credentials_new                     (void);
 gboolean                calls_credentials_update_from_keyfile     (CallsCredentials *self,
                                                                    GKeyFile         *key_file,
                                                                    const char       *name);

src/calls-in-app-notification.c

@@ -143,7 +143,7 @@ calls_in_app_notification_init (CallsInAppNotification *self)
 
 
 CallsInAppNotification *
-calls_in_app_notification_new ()
+calls_in_app_notification_new (void)
 {
   return g_object_new (CALLS_TYPE_IN_APP_NOTIFICATION, NULL);
 }

src/calls-in-app-notification.h

@@ -33,7 +33,7 @@ G_BEGIN_DECLS
 
 G_DECLARE_FINAL_TYPE (CallsInAppNotification, calls_in_app_notification, CALLS, IN_APP_NOTIFICATION, GtkRevealer)
 
-CallsInAppNotification * calls_in_app_notification_new ();
+CallsInAppNotification * calls_in_app_notification_new (void);
 void calls_in_app_notification_show (CallsInAppNotification *self, const gchar *message);
 void calls_in_app_notification_hide (CallsInAppNotification *self);
 

src/calls-notifier.c

@@ -165,7 +165,7 @@ calls_notifier_class_init (CallsNotifierClass *klass)
 }
 
 CallsNotifier *
-calls_notifier_new ()
+calls_notifier_new (void)
 {
   return g_object_new (CALLS_TYPE_NOTIFIER, NULL);
 }

src/calls-notifier.h

@@ -33,7 +33,7 @@ G_BEGIN_DECLS
 
 G_DECLARE_FINAL_TYPE (CallsNotifier, calls_notifier, CALLS, NOTIFIER, GObject);
 
-CallsNotifier *calls_notifier_new ();
+CallsNotifier *calls_notifier_new (void);
 
 G_END_DECLS
 

src/calls-record-store.c

@@ -732,7 +732,7 @@ calls_record_store_init (CallsRecordStore *self)
 
 
 CallsRecordStore *
-calls_record_store_new ()
+calls_record_store_new (void)
 {
   return g_object_new (CALLS_TYPE_RECORD_STORE,
                        "item-type", CALLS_TYPE_CALL_RECORD,