Better fix for snprintf non-termination on windows.

core/src/fxcrt/fx_basic_util.cpp

 // 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
 
 #include "../../include/fxcrt/fx_basic.h"
 #if _FXM_PLATFORM_ != _FXM_PLATFORM_WINDOWS_
 #include <sys/types.h>
 #include <dirent.h>
@@ skipping 151 matching lines @@
             value += fraction_scales[scale] * (str[cc] - '0');
             scale ++;
             if (scale == sizeof fraction_scales / sizeof(FX_FLOAT)) {
                 break;
             }
             cc ++;
         }
     }
     return bNegative ? -value : value;
 }
+
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_ && _MSC_VER < 1900
+void FXSYS_snprintf(char *str, size_t size, _Printf_format_string_ const char* fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    FXSYS_vsnprintf(str, size, fmt, ap);
+    va_end(ap);
+}
+void FXSYS_vsnprintf(char *str, size_t size, const char* fmt, va_list ap)
+{
+    (void) _vsnprintf(str, size, fmt, ap);
+    if (size) {
+        str[size - 1] = 0;
+    }
+}
+#endif  // _FXM_PLATFORM_WINDOWS_ && _MSC_VER < 1900
+
 static FX_BOOL FX_IsDigit(FX_BYTE ch)
 {
     return (ch >= '0' && ch <= '9') ? TRUE : FALSE;
 }
 static FX_BOOL FX_IsXDigit(FX_BYTE ch)
 {
     return (FX_IsDigit(ch) || (ch >= 'A' && ch <= 'F') || (ch >= 'a' && ch <= 'f')) ? TRUE : FALSE;
 }
 static FX_BYTE FX_MakeUpper(FX_BYTE ch)
 {
@@ skipping 296 matching lines @@
 }
 
 CFX_Vector_3by1 CFX_Matrix_3by3::TransformVector(const CFX_Vector_3by1 &v)
 {
     return CFX_Vector_3by1(
         a * v.a + b * v.b + c * v.c,
         d * v.a + e * v.b + f * v.c,
         g * v.a + h * v.b + i * v.c
     );
 }