Rollup merge of #90010 - rusticstuff:vecdeque_with_capacity_in_overflow, r=m-ou-se

Avoid overflow in `VecDeque::with_capacity_in()`.

The overflow only happens if alloc is compiled with overflow checks enabled and the passed capacity is greater or equal 2^(usize::BITS-1). The overflow shadows the expected "capacity overflow" panic leading to a test failure if overflow checks are enabled for std in the CI.

Unblocks [CI: Enable overflow checks for test (non-dist) builds #89776](#89776).

For some reason the overflow is only observable with optimization turned off, but that is a separate issue.

Author: JohnTitor

library/alloc/src/collections/vec_deque/mod.rs

@@ -543,9 +543,9 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> VecDeque<T, A> {
+        assert!(capacity < 1_usize << usize::BITS - 1, "capacity overflow");
         // +1 since the ringbuffer always leaves one space empty
         let cap = cmp::max(capacity + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
-        assert!(cap > capacity, "capacity overflow");
 
         VecDeque { tail: 0, head: 0, buf: RawVec::with_capacity_in(cap, alloc) }
     }