Implement basic lint detecting manual slice copy

Author: marcusklaas

clippy_lints/src/lib.rs

@@ -434,6 +434,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
         loops::FOR_LOOP_OVER_RESULT,
         loops::ITER_NEXT_LOOP,
         loops::NEEDLESS_RANGE_LOOP,
+        loops::MANUAL_MEMCPY,
         loops::NEVER_LOOP,
         loops::REVERSE_RANGE_LOOP,
         loops::UNUSED_COLLECT,