Avoid ordered comparison of pointer with integer to prevent compile error
with GCC 11.

diff --git a/hotspot/src/share/vm/memory/virtualspace.cpp b/hotspot/src/share/vm/memory/virtualspace.cpp
--- a/hotspot/src/share/vm/memory/virtualspace.cpp
+++ b/hotspot/src/share/vm/memory/virtualspace.cpp
@@ -581,7 +581,7 @@ ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, bool large)
   assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size],
          "area must be distinguishable from marks for mark-sweep");
 
-  if (base() > 0) {
+  if (base() != NULL) {
     MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
   }
 }
diff --git a/hotspot/src/share/vm/opto/lcm.cpp b/hotspot/src/share/vm/opto/lcm.cpp
--- a/hotspot/src/share/vm/opto/lcm.cpp
+++ b/hotspot/src/share/vm/opto/lcm.cpp
@@ -39,7 +39,7 @@
 // Check whether val is not-null-decoded compressed oop,
 // i.e. will grab into the base of the heap if it represents NULL.
 static bool accesses_heap_base_zone(Node *val) {
-  if (Universe::narrow_oop_base() > 0) { // Implies UseCompressedOops.
+  if (Universe::narrow_oop_base() != NULL) { // Implies UseCompressedOops.
     if (val && val->is_Mach()) {
       if (val->as_Mach()->ideal_Opcode() == Op_DecodeN) {
         // This assumes all Decodes with TypePtr::NotNull are matched to nodes that