[SPARK-3011][SQL] _temporary directory should be filtered out by sqlContext.parquetFile

fix compile error on hadoop 0.23 for the pull request #1924. 

hmm, a better solution for all of this could be:
no ```val children = fs.listStatus(path)...``` any more

then:
```
val metafile = fs.listStatus(path).find(_.getPath.getName == ParquetFileWriter.PARQUET_METADATA_FILE)
val datafile = fs.listStatus(path).find(isNotHiddenFile(_.getPath.getName))
```
this ```isNotHiddenFile``` simply check like this ```(name(0) != '.' && name(0) != '_')```

then something like:
```
if datafile is not null
  return ParquetFileReader.readFooter(conf, datafile)
else
  return ParquetFileReader.readFooter(conf, metafile)
```

and moreover, @liancheng, after reading carefully following comments, finally i know what you mean "complete Parquet file on HDFS should be directory" https://github.com/apache/spark/pull/2044#issuecomment-52733594

you mean the whole directory is "a single parquet file", and the files in it are "data"? but such a definition is really very very confusing... are you sure about this definition? i just googled, but found noting, only some like "Parquet files are self-describing so the schema is preserved"

so, since they are self-describing, in my mind, each "data-file" in a parquet file folder is also valid parquet-format-file, it should also be able to take as an input source for parquet reader like our Spark SQLContext...