Report pinch gestures

Bug: 251196347
Test: check events received by a custom tester app, and touches shown by
      pointer location overlay
Test: atest inputflinger_tests
Change-Id: I249ca6208091e3c4291c5be68c77339bf5f69a5b
diff --git a/libs/input/Input.cpp b/libs/input/Input.cpp
index 000775b..c247fdb 100644
--- a/libs/input/Input.cpp
+++ b/libs/input/Input.cpp
@@ -74,6 +74,8 @@
             return "TWO_FINGER_SWIPE";
         case MotionClassification::MULTI_FINGER_SWIPE:
             return "MULTI_FINGER_SWIPE";
+        case MotionClassification::PINCH:
+            return "PINCH";
     }
 }