input.h: add missing __INTRODUCED_IN and doc comments.

These were missing from the original commit, and are causing developer
confusion.

Bug: https://github.com/android/ndk/issues/1515
Bug: https://issuetracker.google.com/116830907
Test: treehugger
Change-Id: I4324a0ec9be2b5ce334994b27cd4069d63060d1d
diff --git a/include/android/input.h b/include/android/input.h
index bb98beb..7642215 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -947,9 +947,10 @@
  * and {@link AMotionEvent_fromJava()}.
  * After returning, the specified AInputEvent* object becomes invalid and should no longer be used.
  * The underlying Java object remains valid and does not change its state.
+ *
+ * Available since API level 31.
  */
-
-void AInputEvent_release(const AInputEvent* event);
+void AInputEvent_release(const AInputEvent* event) __INTRODUCED_IN(31);
 
 /*** Accessors for key events only. ***/
 
@@ -1001,8 +1002,10 @@
  * Creates a native AInputEvent* object that is a copy of the specified Java android.view.KeyEvent.
  * The result may be used with generic and KeyEvent-specific AInputEvent_* functions. The object
  * returned by this function must be disposed using {@link AInputEvent_release()}.
+ *
+ * Available since API level 31.
  */
-const AInputEvent* AKeyEvent_fromJava(JNIEnv* env, jobject keyEvent);
+const AInputEvent* AKeyEvent_fromJava(JNIEnv* env, jobject keyEvent) __INTRODUCED_IN(31);
 
 /*** Accessors for motion events only. ***/
 
@@ -1324,8 +1327,10 @@
  * android.view.MotionEvent. The result may be used with generic and MotionEvent-specific
  * AInputEvent_* functions. The object returned by this function must be disposed using
  * {@link AInputEvent_release()}.
+ *
+ * Available since API level 31.
  */
-const AInputEvent* AMotionEvent_fromJava(JNIEnv* env, jobject motionEvent);
+const AInputEvent* AMotionEvent_fromJava(JNIEnv* env, jobject motionEvent) __INTRODUCED_IN(31);
 
 struct AInputQueue;
 /**