removed target/xtend-gen from source folder config

plugins/org.yakindu.sct.generator.c/pom.xml

@@ -45,11 +45,6 @@
 					</filesets>
 				</configuration>
 			</plugin>
-			<plugin>
-				<groupId>org.codehaus.mojo</groupId>
-				<artifactId>build-helper-maven-plugin</artifactId>
-			</plugin>
-			
 			<plugin>
 				<groupId>org.eclipse.xtend</groupId>
 				<artifactId>xtend-maven-plugin</artifactId>