remove getdelim in windows

test=develop

paddle/fluid/string/string_helper.cc

@@ -79,6 +79,7 @@ inline int str_to_float(const char* str, float* v) {
 // A line buffer is maintained. It
 // doesn't need to know the maximum possible length of a line.
 char* LineFileReader::getdelim(FILE* f, char delim) {
+#ifndef __WIN32
   int32_t ret = ::getdelim(&_buffer, &_buf_size, delim, f);
 
   if (ret >= 0) {
@@ -93,6 +94,9 @@ char* LineFileReader::getdelim(FILE* f, char delim) {
     CHECK(feof(f));
     return NULL;
   }
+#else
+  return NULL;
+#endif
 }
 
 }  // end namespace string