improve SurfaceFlinger 'dumpsys' log

list the purgatory, which shows windows that have been closed,
but for which the client still has references.

Change-Id: I5168bb88cb328d5d77d71d0871deb9190f493126
diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index 0c1fcf9..9ddb05f 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -534,6 +534,12 @@
     result.append(buffer);
 }
 
+void LayerBase::shortDump(String8& result, char* scratch, size_t size) const
+{
+    LayerBase::dump(result, scratch, size);
+}
+
+
 // ---------------------------------------------------------------------------
 
 int32_t LayerBaseClient::sIdentity = 1;
@@ -585,6 +591,12 @@
     result.append(buffer);
 }
 
+
+void LayerBaseClient::shortDump(String8& result, char* scratch, size_t size) const
+{
+    LayerBaseClient::dump(result, scratch, size);
+}
+
 // ---------------------------------------------------------------------------
 
 LayerBaseClient::Surface::Surface(