FEAT: Update nodrop for stable needs_drop

nodrop/src/lib.rs

@@ -3,11 +3,10 @@
 //!
 //! - `std`
 //!   - Optional, enabled by default
-//!   - Requires Rust 1.6 *to disable*
 //!   - Use libstd
 //! - `use_needs_drop`
 //!   - Optional
-//!   - Requires nightly channel.
+//!   - Requires Rust 1.21
 //!   - Use `needs_drop` to skip overwriting if not necessary
 //! - `use_union`
 //!   - Optional
@@ -16,8 +15,6 @@
 //!     for example the fact that `NoDrop<T>` never has a destructor anymore.
 //!
 
-#![cfg_attr(feature="use_needs_drop", feature(core_intrinsics))]
-
 #![cfg_attr(not(any(test, feature="std")), no_std)]
 #[cfg(not(any(test, feature="std")))]
 extern crate core as std;
@@ -81,7 +78,7 @@ mod imp {
     #[inline]
     fn needs_drop<T>() -> bool {
         unsafe {
-            ::std::intrinsics::needs_drop::<T>()
+            ::std::mem::needs_drop::<T>()
         }
     }