Change time_t conversion operator to ToTime_t() function

fpdfsdk/include/fsdk_baseannot.h

 // Copyright 2014 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.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef FPDFSDK_INCLUDE_FSDK_BASEANNOT_H_
 #define FPDFSDK_INCLUDE_FSDK_BASEANNOT_H_
 
 #if _FX_OS_ == _FX_ANDROID_
@@ skipping 19 matching lines @@
  public:
   CPDFSDK_DateTime();
   CPDFSDK_DateTime(const CFX_ByteString& dtStr);
   CPDFSDK_DateTime(const CPDFSDK_DateTime& datetime);
   CPDFSDK_DateTime(const FX_SYSTEMTIME& st);
 
   CPDFSDK_DateTime& operator=(const CPDFSDK_DateTime& datetime);
   CPDFSDK_DateTime& operator=(const FX_SYSTEMTIME& st);
   bool operator==(const CPDFSDK_DateTime& datetime) const;
   bool operator!=(const CPDFSDK_DateTime& datetime) const;
-  bool operator>(const CPDFSDK_DateTime& datetime) const;
-  bool operator>=(const CPDFSDK_DateTime& datetime) const;
-  bool operator<(const CPDFSDK_DateTime& datetime) const;
-  bool operator<=(const CPDFSDK_DateTime& datetime) const;
-  operator time_t();
 
   CPDFSDK_DateTime& FromPDFDateTimeString(const CFX_ByteString& dtStr);
   CFX_ByteString ToCommonDateTimeString();
   CFX_ByteString ToPDFDateTimeString();
   void ToSystemTime(FX_SYSTEMTIME& st);
+  time_t ToTime_t() const;
   CPDFSDK_DateTime ToGMT() const;
   CPDFSDK_DateTime& AddDays(short days);
   CPDFSDK_DateTime& AddSeconds(int seconds);
 
   void ResetDateTime();
 
   struct FX_DATETIME {
     int16_t year;
     uint8_t month;
     uint8_t day;
@@ skipping 137 matching lines @@
                        const CFX_ByteString& sAPState = "");
 
  protected:
   CPDF_Annot* m_pAnnot;
 
  private:
   FX_BOOL CreateFormFiller();
 };
 
 #endif  // FPDFSDK_INCLUDE_FSDK_BASEANNOT_H_