Exclude xoo and benchmark modules from analysis

plugins/sonar-xoo-plugin/pom.xml

 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.sonarsource.sonarqube</groupId>
   <packaging>sonar-plugin</packaging>
   <description>Sample of plugin to document and test available APIs</description>
 
+  <properties>
+    <sonar.skip>true</sonar.skip>
+  </properties>
+
   <dependencies>
     <dependency>
       <groupId>com.google.guava</groupId>

server/sonar-server-benchmarks/pom.xml

   <name>SonarQube :: Server :: Benchmarks</name>
 
   <properties>
+    <sonar.skip>true</sonar.skip>
     <skipBenchmarks>true</skipBenchmarks>
     <enableBenchmarkAssertions>false</enableBenchmarkAssertions>
   </properties>