pom: do not build android module unless ANDROID_HOME is present

pom.xml

@@ -7,9 +7,22 @@
     <version>0.0.1-SNAPSHOT</version>
     <packaging>pom</packaging>
  
+    <profiles>
+        <profile>
+            <id>android</id>
+            <activation>
+                <property>
+                    <name>env.ANDROID_HOME</name>
+                </property>
+            </activation>
+            <modules>
+                <module>android</module>
+            </modules>
+        </profile>
+    </profiles>    
+    
     <modules>
        <module>lib</module>
        <module>desktop</module>
-       <module>android</module>
     </modules>
 </project>