java: Specify in build.xml that we are using Java 1.5


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@682453 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/java/build.xml b/lib/java/build.xml
index 75e7451..6f9d0b0 100644
--- a/lib/java/build.xml
+++ b/lib/java/build.xml
@@ -12,7 +12,7 @@
   </target>
 
   <target name="compile" depends="init">
-    <javac srcdir="${src}" destdir="${build}" />
+    <javac srcdir="${src}" destdir="${build}" source="1.5" />
   </target>
 
   <target name="dist" depends="compile">