Remove iter_private.rs

The contents of this file have been moved in #56932 (520e8b0) and the
file should have been removed as well.

src/libcore/iter_private.rs

@@ -1,17 +0,0 @@
-/// An iterator whose items are random accessible efficiently
-///
-/// # Safety
-///
-/// The iterator's .len() and size_hint() must be exact.
-/// `.len()` must be cheap to call.
-///
-/// .get_unchecked() must return distinct mutable references for distinct
-/// indices (if applicable), and must return a valid reference if index is in
-/// 0..self.len().
-#[doc(hidden)]
-pub unsafe trait TrustedRandomAccess : ExactSizeIterator {
-    unsafe fn get_unchecked(&mut self, i: usize) -> Self::Item;
-    /// Returns `true` if getting an iterator element may have
-    /// side effects. Remember to take inner iterators into account.
-    fn may_have_side_effect() -> bool;
-}