Remove the now stable #[feature(question_mark)]

mcarton · mcarton · commit 4cf87a9d4944 · 2016-10-16T14:01:55.000+02:00
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
@@ -4,7 +4,6 @@
 #![feature(collections)]
 #![feature(custom_attribute)]
 #![feature(dotdot_in_tuple_patterns)]
-#![feature(question_mark)]
 #![feature(rustc_private)]
 #![feature(slice_patterns)]
 #![feature(stmt_expr_attributes)]
