8006851: When TieredCompilation is set, max code cache should be bumped to 256mb

Summary: Set ReservedCodeCacheSize to (default value)*5 when TieredCompilation is on.
Reviewed-by: kvn, twisti

src/share/vm/runtime/arguments.cpp

@@ -1086,7 +1086,7 @@ void Arguments::set_tiered_flags() {
   }
   // Increase the code cache size - tiered compiles a lot more.
   if (FLAG_IS_DEFAULT(ReservedCodeCacheSize)) {
-    FLAG_SET_DEFAULT(ReservedCodeCacheSize, ReservedCodeCacheSize * 2);
+    FLAG_SET_DEFAULT(ReservedCodeCacheSize, ReservedCodeCacheSize * 5);
   }
 }