8306459: s390x: Replace NULL to nullptr

Reviewed-by: mdoerr

Author: offamitkumar

src/hotspot/cpu/s390/stubGenerator_s390.cpp

@@ -3155,7 +3155,7 @@ class StubGenerator: public StubCodeGenerator {
 
     // nmethod entry barriers for concurrent class unloading
     BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
-    if (bs_nm != NULL) {
+    if (bs_nm != nullptr) {
       StubRoutines::zarch::_nmethod_entry_barrier = generate_nmethod_entry_barrier();
     }
 

src/hotspot/cpu/s390/templateTable_s390.cpp

@@ -2425,7 +2425,7 @@ void TemplateTable::load_invokedynamic_entry(Register method) {
   __ load_resolved_indy_entry(cache, index);
   __ z_lg(method, Address(cache, in_bytes(ResolvedIndyEntry::method_offset())));
 
-  // The invokedynamic is unresolved iff method is NULL
+  // The invokedynamic is unresolved iff method is null
   __ z_clgij(method, (unsigned long)nullptr, Assembler::bcondNotEqual, resolved); // method != 0, jump to resolved
   Bytecodes::Code code = bytecode();
   // Call to the interpreter runtime to resolve invokedynamic