8323803: ConstantOopReadValue::print_on should print 'null' instead of 'nullptr'

Backport-of: 7620b129888d57514d9ef588e0681f1d43377236

Author: cost0much

src/hotspot/share/code/debugInfo.cpp

@@ -277,7 +277,7 @@ void ConstantOopReadValue::print_on(outputStream* st) const {
   if (value()() != nullptr) {
     value()()->print_value_on(st);
   } else {
-    st->print("nullptr");
+    st->print("null");
   }
 }