Avoid illegal definition of snprintf in VS 2015

third_party/libxml/win32/config.h

 #ifndef __LIBXML_WIN32_CONFIG__
 #define __LIBXML_WIN32_CONFIG__
 
 #define HAVE_CTYPE_H
 #define HAVE_STDARG_H
 #define HAVE_MALLOC_H
 #define HAVE_ERRNO_H
 #define HAVE_STDINT_H
 
 #if defined(_WIN32_WCE)
@@ skipping 78 matching lines @@
         }
     } else {
         return 0;
     }
 }
 #endif
 #endif /* _MSC_VER */
 
 #if defined(_MSC_VER)
 #define mkdir(p,m) _mkdir(p)
+#if _MSC_VER < 1900
 #define snprintf _snprintf
+#endif
 #if _MSC_VER < 1500
 #define vsnprintf(b,c,f,a) _vsnprintf(b,c,f,a)
 #endif
 #elif defined(__MINGW32__)
 #define mkdir(p,m) _mkdir(p)
 #endif
 
 /* Threading API to use should be specified here for compatibility reasons.
    This is however best specified on the compiler's command-line. */
 #if defined(LIBXML_THREAD_ENABLED)
 #if !defined(HAVE_PTHREAD_H) && !defined(HAVE_WIN32_THREADS) && !defined(_WIN32_WCE)
 #define HAVE_WIN32_THREADS
 #endif
 #endif
 
 /* Some third-party libraries far from our control assume the following
    is defined, which it is not if we don't include windows.h. */
 #if !defined(FALSE)
 #define FALSE 0
 #endif
 #if !defined(TRUE)
 #define TRUE (!(FALSE))
 #endif
 
 #endif /* __LIBXML_WIN32_CONFIG__ */