Remove rustc_inherit_overflow_checks from position() in slice iterators

This method implementation can never cause an overflow,
since `i` can never go over the slice's length.

Author: theemathas

library/core/src/slice/iter/macros.rs

@@ -350,7 +350,6 @@ macro_rules! iterator {
             // because this simple implementation generates less LLVM IR and is
             // faster to compile. Also, the `assume` avoids a bounds check.
             #[inline]
-            #[rustc_inherit_overflow_checks]
             fn position<P>(&mut self, mut predicate: P) -> Option<usize> where
                 Self: Sized,
                 P: FnMut(Self::Item) -> bool,