Correct "introduced" version for inline API.

Inlines don't actually have an "introduced" API level since they're
not a part of the system image. Typically they should haven't any
`__INTRODUCED_IN()` annotation (the one that was here unhelpfully
prevents app developers from calling this otherwise available API
until API 34), but in this case the API forwards to an out-of-line API
which was added in API 31, so we mirror that as recommended by
https://developer.android.com/ndk/guides/using-newer-apis#avoiding_repetition_of_api_guards.

Bug: None
Test: treehugger
Change-Id: I80edc4cf2f0f46c14f057fd3c1f4a222646bd15a