Add __INTRODUCED_IN to core <android/*.h> APIs.

Bug: https://github.com/android-ndk/ndk/issues/706
Test: builds
Change-Id: I23db5a2180517045bafabe6fbf783456cbddf21a
diff --git a/include/android/input.h b/include/android/input.h
index f3f5312..3b36d2e 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -56,6 +56,10 @@
 #include <android/keycodes.h>
 #include <android/looper.h>
 
+#if !defined(__INTRODUCED_IN)
+#define __INTRODUCED_IN(__api_level) /* nothing */
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -982,10 +986,8 @@
  */
 int32_t AMotionEvent_getMetaState(const AInputEvent* motion_event);
 
-#if __ANDROID_API__ >= 14
 /** Get the button state of all buttons that are pressed. */
-int32_t AMotionEvent_getButtonState(const AInputEvent* motion_event);
-#endif
+int32_t AMotionEvent_getButtonState(const AInputEvent* motion_event) __INTRODUCED_IN(14);
 
 /**
  * Get a bitfield indicating which edges, if any, were touched by this motion event.
@@ -1050,14 +1052,12 @@
  */
 int32_t AMotionEvent_getPointerId(const AInputEvent* motion_event, size_t pointer_index);
 
-#if __ANDROID_API__ >= 14
 /**
  * Get the tool type of a pointer for the given pointer index.
  * The tool type indicates the type of tool used to make contact such as a
  * finger or stylus, if known.
  */
-int32_t AMotionEvent_getToolType(const AInputEvent* motion_event, size_t pointer_index);
-#endif
+int32_t AMotionEvent_getToolType(const AInputEvent* motion_event, size_t pointer_index) __INTRODUCED_IN(14);
 
 /**
  * Get the original raw X coordinate of this event.
@@ -1147,11 +1147,9 @@
  */
 float AMotionEvent_getOrientation(const AInputEvent* motion_event, size_t pointer_index);
 
-#if __ANDROID_API__ >= 13
 /** Get the value of the request axis for the given pointer index. */
 float AMotionEvent_getAxisValue(const AInputEvent* motion_event,
-        int32_t axis, size_t pointer_index);
-#endif
+        int32_t axis, size_t pointer_index) __INTRODUCED_IN(13);
 
 /**
  * Get the number of historical points in this event.  These are movements that
@@ -1282,14 +1280,12 @@
 float AMotionEvent_getHistoricalOrientation(const AInputEvent* motion_event, size_t pointer_index,
         size_t history_index);
 
-#if __ANDROID_API__ >= 13
 /**
  * Get the historical value of the request axis for the given pointer index
  * that occurred between this event and the previous motion event.
  */
 float AMotionEvent_getHistoricalAxisValue(const AInputEvent* motion_event,
-        int32_t axis, size_t pointer_index, size_t history_index);
-#endif
+        int32_t axis, size_t pointer_index, size_t history_index) __INTRODUCED_IN(13);
 
 
 struct AInputQueue;