libfuzzer: FALSE is not a pointer

BUG=661291
TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2469923002
diff --git a/testing/libfuzzer/pdf_xml_fuzzer.cc b/testing/libfuzzer/pdf_xml_fuzzer.cc
index 199cba2..37b4a76 100644
--- a/testing/libfuzzer/pdf_xml_fuzzer.cc
+++ b/testing/libfuzzer/pdf_xml_fuzzer.cc
@@ -32,7 +32,7 @@
              pNextNode;
              pNextNode = pNextNode->GetNodeItem(CFDE_XMLNode::NextSibling)) {
           if (pNextNode->GetType() == FDE_XMLNODE_Element) {
-            return FALSE;
+            return nullptr;
           }
         }
       }