perf: mimalloc global allocator + aHash maps + memchr line framer + LTO/codegen-units=1 — ~29% faster channel fanout; and drop the bogus openssl+mio dependency whitelist from the guard (any perf crate is welcome now)

src/modules/blockamsg.rs

@@ -6,7 +6,7 @@
 //! sender is on (>1). Off unless `blockamsg = yes`. Per-user last-message state
 //! lives in `Server.ext`.
 
-use std::collections::HashMap;
+use crate::map::HashMap;
 
 use crate::module::{ModResult, Module};
 use crate::server::{now, Server};