RFR 8154280: Zero build fails with undeclared G1LastPLABAverageOccupancy

[Coleen Phillimore]

diff --git a/src/share/vm/gc/g1/g1EvacStats.cpp 
b/src/share/vm/gc/g1/g1EvacStats.cpp
--- a/src/share/vm/gc/g1/g1EvacStats.cpp
+++ b/src/share/vm/gc/g1/g1EvacStats.cpp
@@ -24,6 +24,7 @@

  #include "precompiled.hpp"
  #include "memory/allocation.inline.hpp"
+#include "gc/g1/g1_globals.hpp"
  #include "gc/g1/g1EvacStats.hpp"
  #include "gc/shared/gcId.hpp"
  #include "logging/log.hpp"

Zero build took two hours on linux x64, because I think the newly built 
Zero interpreter is used to make .jmod files.  But it finally builds 
with this change.

Thanks,
Coleen