[534578] Build MAT 1.8 standalone packages with Eclipse Photon

Try previous version of Photon

Change-Id: Ic60b3641c2e44c3e0be6d5c3cde50f673b62a929
diff --git a/org.eclipse.mat.targetdef/mat-photon.target b/org.eclipse.mat.targetdef/mat-photon.target
index da56715..8a44e6f 100644
--- a/org.eclipse.mat.targetdef/mat-photon.target
+++ b/org.eclipse.mat.targetdef/mat-photon.target
@@ -15,7 +15,7 @@
 <unit id="org.eclipse.ui.net" version="0.0.0"/>

 <unit id="org.eclipse.platform" version="0.0.0"/>

 <unit id="org.eclipse.ui.ide.application" version="0.0.0"/>

-<repository location="http://download.eclipse.org/releases/photon"/>

+<repository location="http://download.eclipse.org/releases/photon/201803161000/"/>

 </location>

 <location includeAllPlatforms="false" includeMode="planner" type="InstallableUnit">

 <unit id="com.ibm.dtfj.feature.feature.group" version="0.0.0"/>