HADOOP-17390. Skip license check on lz4 code files (#2478)

The relevant files are `Copyright (C) 2011-present, Yann Collet.` and licensed on the BSD 2-clause license

Contributed by Zhihua Deng.

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/pom.xml

@@ -102,6 +102,8 @@
         <configuration>
           <excludes>
             <exclude>src/main/native/testData/*</exclude>
+            <exclude>**/lz4.h</exclude>
+            <exclude>**/lz4.c</exclude>
           </excludes>
         </configuration>
       </plugin>