use ant to compile jassimp

.travis.yml

@@ -42,4 +42,4 @@ script:
   - echo "=========================================================="
   - echo "REGRESSION TEST FAILS (results/run_regression_suite_failures.csv)"
   - cat ../results/run_regression_suite_failures.csv
-
+  - if [ $ANDROID ]; then ant -v -Dbasedir=${TRAVIS_BUILD_DIR} -f port/jassimp/build.xml ndk-jni ; fi

port/jassimp/build.xml

@@ -5,6 +5,8 @@
 	<property name="build.dir" value="jassimp/bin" />
 	<property name="dist.dir" value="dist" />
 	<property name="doc.dir" value="doc" />
+	<property environment="env"/>
+	<property name="ndk.dir" value="${env.NDK_HOME}" />
 
 	<path id="classpath">
 	</path>
@@ -27,6 +29,12 @@
 		</javah>
 	</target>
 
+	<target name="ndk-jni">
+		<exec executable="${ndk.dir}/ndk-build">
+			<arg line="all NDK_PROJECT_PATH=workspaces/Android-NDK"/>
+		</exec>
+	</target>
+
 	<target name="package" depends="compile">
 		<jar destfile="${dist.dir}/jassimp.jar" basedir="${build.dir}">
 		</jar>