Optimize core::ptr::align_offset

- As explained in the comment inside mod_inv, it is valid to work mod
  `usize::max_value()` right until the end.

Author: amosonn

src/libcore/ptr/mod.rs

@@ -1081,8 +1081,7 @@ pub(crate) unsafe fn align_offset<T: Sized>(p: *const T, a: usize) -> usize {
                 // uses e.g., subtraction `mod n`. It is entirely fine to do them `mod
                 // usize::max_value()` instead, because we take the result `mod n` at the end
                 // anyway.
-                inverse = inverse.wrapping_mul(2usize.wrapping_sub(x.wrapping_mul(inverse)))
-                    & (going_mod - 1);
+                inverse = inverse.wrapping_mul(2usize.wrapping_sub(x.wrapping_mul(inverse)));
                 if going_mod >= m {
                     return inverse & (m - 1);
                 }