Add spring-build 2.2.3 and ensure build succeeds.

spring-build was previously included via an svn:external. Adding
directly to the source tree under Git to avoid the need for a git
submodule.

In order to build from any earlier commit, it is recommended to
export spring-build or symlink an existing copy into the root
of the spring-framework project and then build normally.

$ svn export https://src.springsource.org/svn/spring-build/tags/project-build-2.2.3 spring-build

spring-build/war/package.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project name="package-war">
+
+	<import file="common.xml"/>
+	<import file="../common/package.xml"/>
+
+<!-- Macros -->
+	<macrodef name="dist-jar">
+		<attribute name="output.dir" default="${package.dist.dir}"/>
+		<sequential>
+			<mkdir dir="@{output.dir}"/>
+			<copy file="${war.output.file}" tofile="@{output.dir}/${package.war.output.file}"/>
+		</sequential>
+	</macrodef>
+
+</project>