Gio::Application: Destructor: Use noexcept in the implementation too.

Bug #758798 (https://bugzilla.gnome.org/show_bug.cgi?id=758798)

diff --git a/gio/src/application.ccg b/gio/src/application.ccg
index 9fb5866..c7488ac 100644
--- a/gio/src/application.ccg
+++ b/gio/src/application.ccg
@@ -278,7 +278,7 @@ Application::Application(const Glib::ustring& application_id, ApplicationFlags f
 
 }
 
-Application::~Application()
+Application::~Application() noexcept
 {
   // Delete all OptionArgCallbackData instances that belong to this application.
   std::lock_guard<std::mutex> lock(option_arg_callback_data_mutex);