6884552: remove some unnecessary #ifdef's introduced in the fix for 4957990

Summary: Removed the unnecessary #ifdef's which were interfering with the build of the Zero-assembler port
Reviewed-by: ysr, jcoomes

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

@@ -2752,7 +2752,6 @@ PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
   cm->revisit_klass_stack()->push(k);
 }
 
-#if ( defined(COMPILER1) || defined(COMPILER2) )
 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) {
   cm->revisit_mdo_stack()->push(p);
 }
@@ -2778,7 +2777,6 @@ void PSParallelCompact::follow_mdo_weak_refs() {
     follow_stack(cm);
   }
 }
-#endif //  ( COMPILER1 || COMPILER2 )
 
 
 #ifdef VALIDATE_MARK_SWEEP

src/share/vm/gc_implementation/shared/markSweep.cpp

@@ -73,7 +73,6 @@ void MarkSweep::follow_weak_klass_links() {
   follow_stack();
 }
 
-#if ( defined(COMPILER1) || defined(COMPILER2) )
 void MarkSweep::revisit_mdo(DataLayout* p) {
   _revisit_mdo_stack->push(p);
 }
@@ -92,7 +91,6 @@ void MarkSweep::follow_mdo_weak_refs() {
   }
   follow_stack();
 }
-#endif //  ( COMPILER1 || COMPILER2 )
 
 MarkSweep::FollowRootClosure  MarkSweep::follow_root_closure;