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

Author: Dan Albert

libs/nativewindow/include/android/native_window.h

@@ -366,14 +366,13 @@ int32_t ANativeWindow_setFrameRateWithChangeStrategy(ANativeWindow* window, floa
  *
  * See ANativeWindow_setFrameRateWithChangeStrategy().
  *
- * Available since API level 34.
+ * Available since API level 31.
  *
  * \param window pointer to an ANativeWindow object.
  *
  * \return 0 for success, -EINVAL if the window value is invalid.
  */
-inline int32_t ANativeWindow_clearFrameRate(ANativeWindow* window)
-        __INTRODUCED_IN(__ANDROID_API_U__) {
+inline int32_t ANativeWindow_clearFrameRate(ANativeWindow* window) __INTRODUCED_IN(31) {
     return ANativeWindow_setFrameRateWithChangeStrategy(window, 0,
             ANATIVEWINDOW_FRAME_RATE_COMPATIBILITY_DEFAULT,
             ANATIVEWINDOW_CHANGE_FRAME_RATE_ONLY_IF_SEAMLESS);