add feature gate to some benchmarks

src/test/bench/shootout-fasta.rs

@@ -38,7 +38,7 @@
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 // OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#![feature(slicing_syntax)]
+#![feature(associated_types, slicing_syntax)]
 
 use std::cmp::min;
 use std::io::{BufferedWriter, File};

src/test/bench/shootout-k-nucleotide.rs

@@ -40,7 +40,7 @@
 
 // ignore-android see #10393 #13206
 
-#![feature(slicing_syntax)]
+#![feature(associated_types, slicing_syntax)]
 
 use std::ascii::OwnedAsciiExt;
 use std::slice;

src/test/bench/shootout-meteor.rs

@@ -40,6 +40,8 @@
 
 // no-pretty-expanded FIXME #15189
 
+#![feature(associated_types)]
+
 use std::sync::mpsc::channel;
 use std::sync::Arc;
 use std::thread::Thread;

src/test/bench/shootout-reverse-complement.rs

@@ -40,7 +40,7 @@
 
 // ignore-android see #10393 #13206
 
-#![feature(slicing_syntax, unboxed_closures)]
+#![feature(associated_types, slicing_syntax, unboxed_closures)]
 
 extern crate libc;