Add missing about.html back to p2 source feature.
diff --git a/p2/org.eclipse.cdt.p2/build.properties b/p2/org.eclipse.cdt.p2/build.properties
index 0d4b2e0..88ef4bb 100644
--- a/p2/org.eclipse.cdt.p2/build.properties
+++ b/p2/org.eclipse.cdt.p2/build.properties
@@ -19,3 +19,4 @@
                plugin.properties,\
                about.properties,\
                cdt_logo_icon32.png
+src.includes = about.html