[CIR] Lower __atomic_is_lock_free / __c11_atomic_is_lock_free (#205862)

`__atomic_is_lock_free` and `__c11_atomic_is_lock_free` were routed to
`errorNYI` in CIRGen, so `std::atomic<T>::is_lock_free()` failed to
compile under `-fclangir` whenever the query wasn't constant-folded --
which is what the libcxx atomics lock-free tests hit.

This mirrors classic CodeGen (`CGBuiltin.cpp`): emit a call to the
runtime entry `bool __atomic_is_lock_free(size_t size, void *ptr)`.
`__atomic_is_lock_free` forwards its pointer argument;
`__c11_atomic_is_lock_free` passes a null pointer, since an `_Atomic`
object is always suitably aligned. `__atomic_test_and_set` /
`__atomic_clear` stay NYI.

The lowered call omits the `noundef`/`zeroext` argument and return
attributes classic emits, and the declaration picks up `dso_local`.
That's the existing CIR libcall attribute gap, so the test uses split
`LLVMCIR`/`OGCG` prefixes where the two diverge and a shared skeleton
where they match.