replace if let mutex lint removed in rebase of lib.rs file

Author: DevinR528

clippy_lints/src/lib.rs

@@ -1055,6 +1055,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box dereference::Dereferencing);
     store.register_late_pass(|| box future_not_send::FutureNotSend);
     store.register_late_pass(|| box utils::internal_lints::CollapsibleCalls);
+    store.register_late_pass(|| box if_let_mutex::IfLetMutex);
     store.register_late_pass(|| box macro_use::MacroUseImports::default());
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![