Get rid of NULLs in core/

core/fxcodec/codec/fx_codec_fax.cpp

Index: core/fxcodec/codec/fx_codec_fax.cpp
diff --git a/core/fxcodec/codec/fx_codec_fax.cpp b/core/fxcodec/codec/fx_codec_fax.cpp
index 97b7ee2ad6e545869b4ae5494a21fd2350402424..f9f876dd5b9e408e3074a475771473b332fad11f 100644
--- a/core/fxcodec/codec/fx_codec_fax.cpp
+++ b/core/fxcodec/codec/fx_codec_fax.cpp
@@ -621,8 +621,8 @@ class CCodec_FaxDecoder : public CCodec_ScanlineDecoder {
 };
 
 CCodec_FaxDecoder::CCodec_FaxDecoder() {
-  m_pScanlineBuf = NULL;
-  m_pRefBuf = NULL;
+  m_pScanlineBuf = nullptr;
+  m_pRefBuf = nullptr;
 }
 CCodec_FaxDecoder::~CCodec_FaxDecoder() {
   FX_Free(m_pScanlineBuf);
@@ -671,7 +671,7 @@ uint8_t* CCodec_FaxDecoder::v_GetNextLine() {
   int bitsize = m_SrcSize * 8;
   FaxSkipEOL(m_pSrcBuf, bitsize, bitpos);
   if (bitpos >= bitsize) {
-    return NULL;
+    return nullptr;
   }
   FXSYS_memset(m_pScanlineBuf, 0xff, m_Pitch);
   if (m_Encoding < 0) {