IMPALA-1066: Fix bad free in Min()/Max() of strings.
IMPALA-1066: Fix bad free in Min()/Max() of strings.

Change-Id: If66844a88accdc369458ab92f033eef50775d69e
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3373
Reviewed-by: Nong Li <99a5e5f8f5911755b88e0b536d46aafa102bed41@cloudera.com>
Tested-by: jenkins

scalingdata/Impala,cchanning/Impala,caseyching/Impala,bratatidas9/Impala-1,cloudera/recordservice,cloudera/recordservice,ibmsoe/ImpalaPPC,cgvarela/Impala,bowlofstew/Impala,lnliuxing/Impala,theyaa/Impala,bratatidas9/Impala-1,tempbottle/Impala,tempbottle/Impala,grundprinzip/Impala,lirui-intel/Impala,ibmsoe/ImpalaPPC,brightchen/Impala,brightchen/Impala,bratatidas9/Impala-1,gerashegalov/Impala,scalingdata/Impala,XiaominZhang/Impala,cloudera/recordservice,henryr/Impala,brightchen/Impala,gerashegalov/Impala,lirui-intel/Impala,tempbottle/Impala,bratatidas9/Impala-1,brightchen/Impala,rdblue/Impala,rdblue/Impala,theyaa/Impala,XiaominZhang/Impala,lnliuxing/Impala,ImpalaToGo/ImpalaToGo,cchanning/Impala,grundprinzip/Impala,grundprinzip/Impala,ImpalaToGo/ImpalaToGo,cgvarela/Impala,tempbottle/Impala,cloudera/recordservice,ImpalaToGo/ImpalaToGo,grundprinzip/Impala,ibmsoe/ImpalaPPC,ibmsoe/ImpalaPPC,rdblue/Impala,rdblue/Impala,lirui-intel/Impala,XiaominZhang/Impala,caseyching/Impala,tempbottle/Impala,lnliuxing/Impala,bowlofstew/Impala,lnliuxing/Impala,cloudera/recordservice,lnliuxing/Impala,lirui-intel/Impala,cchanning/Impala,gerashegalov/Impala,rdblue/Impala,XiaominZhang/Impala,XiaominZhang/Impala,henryr/Impala,bratatidas9/Impala-1,kapilrastogi/Impala,cgvarela/Impala,bowlofstew/Impala,cgvarela/Impala,ibmsoe/ImpalaPPC,kapilrastogi/Impala,grundprinzip/Impala,cgvarela/Impala,bowlofstew/Impala,XiaominZhang/Impala,cchanning/Impala,tempbottle/Impala,gerashegalov/Impala,cchanning/Impala,ibmsoe/ImpalaPPC,theyaa/Impala,caseyching/Impala,henryr/Impala,caseyching/Impala,bratatidas9/Impala-1,theyaa/Impala,brightchen/Impala,bowlofstew/Impala,cgvarela/Impala,cchanning/Impala,bowlofstew/Impala,tempbottle/Impala,ibmsoe/ImpalaPPC,placrosse/ImpalaToGo,scalingdata/Impala,theyaa/Impala,ImpalaToGo/ImpalaToGo,brightchen/Impala,gerashegalov/Impala,theyaa/Impala,cgvarela/Impala,scalingdata/Impala,lirui-intel/Impala,placrosse/ImpalaToGo,caseyching/Impala,gerashegalov/Impala,cchanning/Impala,caseyching/Impala,ImpalaToGo/ImpalaToGo,rdblue/Impala,lnliuxing/Impala,ImpalaToGo/ImpalaToGo,kapilrastogi/Impala,placrosse/ImpalaToGo,placrosse/ImpalaToGo,scalingdata/Impala,kapilrastogi/Impala,scalingdata/Impala,grundprinzip/Impala,XiaominZhang/Impala,henryr/Impala,placrosse/ImpalaToGo,theyaa/Impala,lirui-intel/Impala,henryr/Impala,henryr/Impala,kapilrastogi/Impala,gerashegalov/Impala,lnliuxing/Impala,placrosse/ImpalaToGo,caseyching/Impala,lirui-intel/Impala,bratatidas9/Impala-1,kapilrastogi/Impala,rdblue/Impala,bowlofstew/Impala,brightchen/Impala,kapilrastogi/Impala,cloudera/recordservice,cloudera/recordservice