Get rid of NULLs in fpdfsdk/

fpdfsdk/fpdf_dataavail.cpp

Index: fpdfsdk/fpdf_dataavail.cpp
diff --git a/fpdfsdk/fpdf_dataavail.cpp b/fpdfsdk/fpdf_dataavail.cpp
index dc6efbc4368ddbec5be1b4eca5891416ef38b99a..878271efc9349670f55f6b7a050d613a3bfedca9 100644
--- a/fpdfsdk/fpdf_dataavail.cpp
+++ b/fpdfsdk/fpdf_dataavail.cpp
@@ -37,7 +37,7 @@ static_assert(IPDF_DataAvail::FormNotExist == PDF_FORM_NOTEXIST,
 
 class CFPDF_FileAvailWrap : public IPDF_DataAvail::FileAvail {
  public:
-  CFPDF_FileAvailWrap() { m_pfileAvail = NULL; }
+  CFPDF_FileAvailWrap() { m_pfileAvail = nullptr; }
   ~CFPDF_FileAvailWrap() override {}
 
   void Set(FX_FILEAVAIL* pfileAvail) { m_pfileAvail = pfileAvail; }
@@ -53,7 +53,7 @@ class CFPDF_FileAvailWrap : public IPDF_DataAvail::FileAvail {
 
 class CFPDF_FileAccessWrap : public IFX_FileRead {
  public:
-  CFPDF_FileAccessWrap() { m_pFileAccess = NULL; }
+  CFPDF_FileAccessWrap() { m_pFileAccess = nullptr; }
   ~CFPDF_FileAccessWrap() override {}
 
   void Set(FPDF_FILEACCESS* pFile) { m_pFileAccess = pFile; }
@@ -91,7 +91,7 @@ class CFPDF_DownloadHintsWrap : public IPDF_DataAvail::DownloadHints {
 
 class CFPDF_DataAvail {
  public:
-  CFPDF_DataAvail() { m_pDataAvail = NULL; }
+  CFPDF_DataAvail() { m_pDataAvail = nullptr; }
 
   ~CFPDF_DataAvail() { delete m_pDataAvail; }