Deprecation warnings for deprecated syntax

RELNOTES: Global varaiables HOST_CFG and DATA_CFG are deprecated in favor of strings "host" 
and "data.
Argument `cfg = "host"` or `cfg = "data"` is mandatory if `executable = True` is provided for a label.

--
MOS_MIGRATED_REVID=133285197
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
index f7ea9f9..177c052 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
@@ -777,7 +777,7 @@
     return knownGlobalVariables != null && knownGlobalVariables.contains(varname);
   }
 
-  void handleEvent(Event event) {
+  public void handleEvent(Event event) {
     eventHandler.handle(event);
   }