Extend the for loop to use all samples

Currently, the last sample is treated in a special manner (consistent
with the docs for MotionEvent).
However, the public api of MotionEvent also work fine if the element at
index [historySize] is accessed.

Therefore, calling event.getX() is the same as calling
event.getHistoricalX(historySize).

To simplify the code, remove the redundant code and instead extend the
loop by 1.

Bug: 167946721
Test: atest libinput_tests
Change-Id: Icc1fff1b0f16d63d7d0eb33e5977a3b3b440f562
diff --git a/include/input/Input.h b/include/input/Input.h
index 9feab7b..258adae 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -578,10 +578,18 @@
 
     float getAxisValue(int32_t axis, size_t pointerIndex) const;
 
+    /**
+     * Get the X coordinate of the latest sample in this MotionEvent for pointer 'pointerIndex'.
+     * Identical to calling getHistoricalX(pointerIndex, getHistorySize()).
+     */
     inline float getX(size_t pointerIndex) const {
         return getAxisValue(AMOTION_EVENT_AXIS_X, pointerIndex);
     }
 
+    /**
+     * Get the Y coordinate of the latest sample in this MotionEvent for pointer 'pointerIndex'.
+     * Identical to calling getHistoricalX(pointerIndex, getHistorySize()).
+     */
     inline float getY(size_t pointerIndex) const {
         return getAxisValue(AMOTION_EVENT_AXIS_Y, pointerIndex);
     }