www/waterfox: Fix build with rust 1.95.0

Import part of upstream patch [1] to fix the following error,
upstream PR at [2]:

error[E0599]: no method named select found for struct Mask<T, N> in the current scope

--> third_party/rust/encoding_rs/src/x_user_defined.rs:23:56

[1] https://hg-edge.mozilla.org/mozilla-central/rev/ec1dd05fd578
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=2033279

PR: 294615
Approved by: portmgr (build fix blanket)