Get rid of NULLs in core/

core/fxcodec/codec/fx_codec.cpp

Index: core/fxcodec/codec/fx_codec.cpp
diff --git a/core/fxcodec/codec/fx_codec.cpp b/core/fxcodec/codec/fx_codec.cpp
index f0f03ab0e93f53e88513dd09e93ce752112b7ead..054fecfef19d7ed783a9304b89d7ee81d2d3a90a 100644
--- a/core/fxcodec/codec/fx_codec.cpp
+++ b/core/fxcodec/codec/fx_codec.cpp
@@ -100,7 +100,7 @@ FX_BOOL CCodec_BasicModule::RunLengthEncode(const uint8_t* src_buf,
 extern "C" double FXstrtod(const char* nptr, char** endptr) {
   double ret = 0.0;
   const char* ptr = nptr;
-  const char* exp_ptr = NULL;
+  const char* exp_ptr = nullptr;
   int e_number = 0, e_signal = 0, e_point = 0, is_negative = 0;
   int exp_ret = 0, exp_sig = 1, fra_ret = 0, fra_count = 0, fra_base = 1;
   if (!nptr) {
@@ -243,8 +243,8 @@ class CCodec_RLScanlineDecoder : public CCodec_ScanlineDecoder {
   uint8_t m_Operator;
 };
 CCodec_RLScanlineDecoder::CCodec_RLScanlineDecoder()
-    : m_pScanline(NULL),
-      m_pSrcBuf(NULL),
+    : m_pScanline(nullptr),
+      m_pSrcBuf(nullptr),
       m_SrcSize(0),
       m_dwLineBytes(0),
       m_SrcOffset(0),
@@ -322,7 +322,7 @@ uint8_t* CCodec_RLScanlineDecoder::v_GetNextLine() {
     GetNextOperator();
   } else {
     if (m_bEOD) {
-      return NULL;
+      return nullptr;
     }
   }
   FXSYS_memset(m_pScanline, 0, m_Pitch);