[MINOR] Further apache.commons.lang3 changes

A recently merged PR added two occurrences of apache.commons.lang version 2 imports which makes compilation fail on newer systems that don't have this old package in their cache.
diff --git a/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReader.java b/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReader.java
index 9465398..b31630c 100644
--- a/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReader.java
+++ b/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReader.java
@@ -19,7 +19,7 @@
 
 package org.apache.sysds.runtime.iogen.template;
 
-import org.apache.commons.lang.mutable.MutableInt;
+import org.apache.commons.lang3.mutable.MutableInt;
 import org.apache.hadoop.io.LongWritable;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.mapred.FileInputFormat;
diff --git a/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReaderParallel.java b/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReaderParallel.java
index 26968d7..30ddc02 100644
--- a/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReaderParallel.java
+++ b/src/main/java/org/apache/sysds/runtime/iogen/template/MatrixGenerateReaderParallel.java
@@ -19,7 +19,7 @@
 
 package org.apache.sysds.runtime.iogen.template;
 
-import org.apache.commons.lang.mutable.MutableInt;
+import org.apache.commons.lang3.mutable.MutableInt;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.io.LongWritable;