Ask for vec_dec_retain feature in libcollectionstest.

Author: Stebalien

src/libcollectionstest/lib.rs

@@ -21,6 +21,7 @@
 #![feature(into_cow)]
 #![feature(step_by)]
 #![cfg_attr(test, feature(str_char))]
+#![cfg_attr(test, feature(vec_deque_retain))]
 
 #[macro_use] extern crate log;