ircd:Ⓜ️:event::fetch: Improve codegen w/ dtor linkage.

include/ircd/m/event/fetch.h

@@ -69,6 +69,7 @@ struct ircd::m::event::fetch
 	fetch(const id &, const opts & = default_opts);
 	fetch(const idx &, const opts & = default_opts);
 	fetch(const opts & = default_opts);
+	~fetch() noexcept;
 };
 
 /// Event Fetch Options.

matrix/event_fetch.cc

@@ -258,6 +258,12 @@ ircd::m::event::fetch::fetch(const opts &opts)
 {
 }
 
+// array of db::cell::~cell()
+ircd::m::event::fetch::~fetch()
+noexcept
+{
+}
+
 [[gnu::visibility("hidden")]]
 bool
 ircd::m::event::fetch::assign_from_json(const string_view &key)