Remove std namespace directive declarations.
Remove std namespace directive declarations.

Change-Id: I1530d8664d120b6bef86452f22c2139fa08fcf54
Reviewed-on: http://gerrit.cloudera.org:8080/361
Reviewed-by: Juan Yu <34a62e20de6070542c7bca4f0f49d6e4786ad51e@cloudera.com>
Tested-by: Internal Jenkins

michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala