Fix for b/4380963 Log spam from widevine drm on I/O error WVMFileSource: mDataSource-readAt returned error -1004

Change-Id: I001d496bc59aa6465c20f85dfade364f4cca33de

proprietary/wvm/include/WVMFileSource.h

@@ -43,6 +43,7 @@ public:
 private:
     sp<DataSource> mDataSource;
     unsigned long long mOffset;
+    bool mLogOnce;
 };
 
 };