[pom] Correct direct argline usage

Author: hazendaz

pom.xml

@@ -113,7 +113,7 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
         <configuration>
-            <argLine>-Xms1024m -Xmx1024m</argLine>
+            <argLine>${argLine} -Xms1024m -Xmx1024m</argLine>
         </configuration>
       </plugin>
     </plugins>