remove lib and native/clesperantoj/cppbuild during clean phase

pom.xml

@@ -147,6 +147,21 @@
 		</pluginManagement>
 		<!-- add gen source directory which will contain the java wrapper code generated by the javacpp parser  -->
 		<plugins>
+			<!-- plugin that in the clean phase removes c++ created dirs -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-clean-plugin</artifactId>
+                <configuration>
+                    <filesets>
+                        <fileset>
+                            <directory>lib</directory>
+                        </fileset>
+                        <fileset>
+                            <directory>native/clesperantoj/cppbuild</directory>
+                        </fileset>
+                    </filesets>
+                </configuration>
+            </plugin>
 	        <!-- Execute cppbuild.sh to build cleperantoj a wrapper to clesperato.hpp -->
 			<plugin>
 				<artifactId>exec-maven-plugin</artifactId>