Allow gc to remove test results from memory as these can consume a lot of memory

maven-plugin/src/main/java/hudson/maven/reporters/SurefireArchiver.java

@@ -139,7 +139,9 @@ public class SurefireArchiver extends MavenReporter {
                 
                 // final reference in order to serialize it:
                 final TestResult r = result;
-    
+                //allow gc to free some memory
+                result = null;
+                
                 int failCount = build.execute(new BuildCallable<Integer, IOException>() {
                         private static final long serialVersionUID = -1023888330720922136L;