Update lint_message_convention test to allow clippy "help" message

Author: GuillaumeGomez

tests/lint_message_convention.rs

@@ -44,6 +44,7 @@ impl Message {
                 ".*AT&T x86 assembly syntax used",
                 "note: Clippy version: .*",
                 "the compiler unexpectedly panicked. this is a bug.",
+                "internal compiler error:",
             ])
             .unwrap()
         });