libfuzzer: FALSE is not a pointer

testing/libfuzzer/pdf_xml_fuzzer.cc

 // Copyright 2016 The PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <memory>
 
 #include "core/fxcrt/fx_basic.h"
@@ skipping 14 matching lines @@
   for (CFDE_XMLNode* pXMLNode =
            pXMLFakeRoot->GetNodeItem(CFDE_XMLNode::FirstChild);
        pXMLNode; pXMLNode = pXMLNode->GetNodeItem(CFDE_XMLNode::NextSibling)) {
     if (pXMLNode->GetType() == FDE_XMLNODE_Element) {
       if (bVerifyWellFormness) {
         for (CFDE_XMLNode* pNextNode =
                  pXMLNode->GetNodeItem(CFDE_XMLNode::NextSibling);
              pNextNode;
              pNextNode = pNextNode->GetNodeItem(CFDE_XMLNode::NextSibling)) {
           if (pNextNode->GetType() == FDE_XMLNODE_Element) {
-            return FALSE;
+            return nullptr;
           }
         }
       }
       return pXMLNode;
     }
   }
   return nullptr;
 }
 
 }  // namespace
@@ skipping 16 matching lines @@
   if (!doc->LoadXML(parser.release()))
     return 0;
 
   int32_t load_result = doc->DoLoad(nullptr);
   if (load_result < 100)
     return 0;
 
   (void)XFA_FDEExtension_GetDocumentNode(doc.get());
   return 0;
 }