Auto merge of #107987 - EFanZh:inline-poll-methods, r=Mark-Simulacrum

Inline `Poll` methods

With `opt-level="z"`, the `Poll::map*` methods are sometimes not inlined (see <https://godbolt.org/z/ca5ajKTEK>). This PR adds `#[inline]` to these methods. I have a project that can benefit from this change, but do we want to enable this behavior universally?

Fixes #101080.

Author: bors