[newsblur] keep a reference the complete URL
[newsblur] keep a reference the complete URL

otherwise the temporary object we get .c_str() from gets destroyed
leaving us with an invalid pointer.

der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,x4121/newsbeuter,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,x4121/newsbeuter,newsboat/newsboat,x4121/newsbeuter,newsboat/newsboat,der-lyse/newsboat,x4121/newsbeuter,der-lyse/newsboat,der-lyse/newsboat