Fix an issue with the setupDevWorkspace target on windows.

editor/tools/features/com.google.dart.tools.deploy.feature_releng/build_rcp.xml

 <!--
 This build script will build the Dart RCP and Dart update site.  
 
 This script will setup the PDE build structure and then call into the PDE
 build system.  The PDE build system has to run under Eclipse.
 -->
 <project name="build_dart" default="build_rcp">
     
     <import file="build-common.xml" />
 
@@ skipping 228 matching lines @@
     <target name="installSdk" unless="build.dart.sdk" depends="setOS">
         <echoProperty propertyname="build.dart.sdk"/>
 
         <get src="http://gsdview.appspot.com/dart-editor-archive-continuous/latest/dartsdk-${osfamily}-32.zip"
              dest="${build.dart.sdk.zip}"
              usetimestamp="true" />
         
         <echo message="unzipping ${build.dart.sdk.zip} to ${build.stage.include.dir}"/>
         <mkdir dir="${build.stage.include.dir}" />
         <delete dir="${build.stage.include.dir}/dart-sdk"/>
-        <exec executable="unzip" dir="${build.stage.include.dir}">
-            <arg value="-q"/>
+        <exec executable="${unzip.tool}" dir="${build.stage.include.dir}">
+            <arg value="${unzip.arg}"/>
             <arg value="${build.dart.sdk.zip}"/>
         </exec>
     </target>
     
     <!-- - - - - - - - - - - - - - - - - - 
           target: setupDevWorkspace
          - - - - - - - - - - - - - - - - - -->
     <target name="setupDevWorkspace" 
             depends="initDevWorkspace, buildSamples, installSdk">
     </target>
@@ skipping 197 matching lines @@
 }</echo>
     </target>
 
     <!-- - - - - - - - - - - - - - - - - - 
           target: doDeploy_rcp                      
          - - - - - - - - - - - - - - - - - -->
     <target name="doDeploy_rcp" depends="init, setupBuild, doBuild_rcp, package_rcp">
     </target>
 
 </project>