6614597: Performance variability in jvm2008 xml.validation

Fix incorrect marking of methods as not compilable.

Reviewed-by: never

hotspot/src/share/vm/oops/methodDataOop.hpp

@@ -1391,6 +1391,9 @@ public:
   }
   void inc_decompile_count() {
     _nof_decompiles += 1;
+    if (decompile_count() > (uint)PerMethodRecompilationCutoff) {
+      method()->set_not_compilable();
+    }
   }
 
   // Support for code generation