Fix TouchHistoryMath import

Summary:
The reference needed to be updated after the file was moved in this commit:
06085d3836

Otherwise, results in the packager failing with the following error:
> Unable to resolve module TouchHistoryMath from /node_modules/react-native/Libraries/Interaction/PanResponder.js: Module TouchHistoryMath does not exist in the Haste module map
Closes https://github.com/facebook/react-native/pull/18732

Differential Revision: D7547181

Pulled By: sebmarkbage

fbshipit-source-id: 78028c2f46faa2ce130a1a0c25fcaca47d2516a8

Libraries/Interaction/PanResponder.js

@@ -10,7 +10,7 @@
 'use strict';
 
 const InteractionManager = require('./InteractionManager');
-const TouchHistoryMath = require('TouchHistoryMath');
+const TouchHistoryMath = require('./TouchHistoryMath');
 
 const currentCentroidXOfTouchesChangedAfter = TouchHistoryMath.currentCentroidXOfTouchesChangedAfter;
 const currentCentroidYOfTouchesChangedAfter = TouchHistoryMath.currentCentroidYOfTouchesChangedAfter;