update rust toolchain

It comes with a bunch of new lints (yay!) so I fixed them all so CI will
keep working.

Also apparently something about linking changed because I had to change
the checks for deciding the linker flags for static x86_64 builds to
keep working.

src/service/users/mod.rs

@@ -138,12 +138,18 @@ impl Service {
             cached.lists.insert(list_id.clone(), list.clone());
         }
 
-        cached
-            .subscriptions
-            .extend(request.room_subscriptions.clone().into_iter());
-        request
-            .room_subscriptions
-            .extend(cached.subscriptions.clone().into_iter());
+        cached.subscriptions.extend(
+            request
+                .room_subscriptions
+                .iter()
+                .map(|(k, v)| (k.clone(), v.clone())),
+        );
+        request.room_subscriptions.extend(
+            cached
+                .subscriptions
+                .iter()
+                .map(|(k, v)| (k.clone(), v.clone())),
+        );
 
         request.extensions.e2ee.enabled = request
             .extensions