Flush stdout and stderr prior to exiting child process.
Flush stdout and stderr prior to exiting child process.

This fixes a confusing bug that we ran into where the output from
certain child processes wouldn't appear when running `lint-all` via
`ssh` (without a tty) into the Vagrant environment.

tommyip/zulip,mohsenSy/zulip,ryanbackman/zulip,Diptanshu8/zulip,eeshangarg/zulip,arpith/zulip,Jianchun1/zulip,jackrzhang/zulip,jackrzhang/zulip,jrowan/zulip,cosmicAsymmetry/zulip,brainwane/zulip,jainayush975/zulip,j831/zulip,PhilSk/zulip,punchagan/zulip,jrowan/zulip,peguin40/zulip,reyha/zulip,amanharitsh123/zulip,jphilipsen05/zulip,dawran6/zulip,TigorC/zulip,ryanbackman/zulip,TigorC/zulip,cosmicAsymmetry/zulip,vaidap/zulip,vikas-parashar/zulip,TigorC/zulip,PhilSk/zulip,rishig/zulip,samatdav/zulip,aakash-cr7/zulip,amyliu345/zulip,zacps/zulip,KingxBanana/zulip,niftynei/zulip,Diptanshu8/zulip,ahmadassaf/zulip,dawran6/zulip,Jianchun1/zulip,brainwane/zulip,SmartPeople/zulip,Galexrt/zulip,dattatreya303/zulip,andersk/zulip,sharmaeklavya2/zulip,souravbadami/zulip,Jianchun1/zulip,PhilSk/zulip,amanharitsh123/zulip,samatdav/zulip,mohsenSy/zulip,kou/zulip,arpith/zulip,punchagan/zulip,hackerkid/zulip,hackerkid/zulip,rishig/zulip,mahim97/zulip,susansls/zulip,Galexrt/zulip,amanharitsh123/zulip,aakash-cr7/zulip,joyhchen/zulip,eeshangarg/zulip,vikas-parashar/zulip,sonali0901/zulip,sonali0901/zulip,synicalsyntax/zulip,brockwhittaker/zulip,andersk/zulip,showell/zulip,umkay/zulip,dattatreya303/zulip,krtkmj/zulip,hackerkid/zulip,aakash-cr7/zulip,mahim97/zulip,jackrzhang/zulip,j831/zulip,timabbott/zulip,kou/zulip,JPJPJPOPOP/zulip,dhcrzf/zulip,ahmadassaf/zulip,umkay/zulip,ryanbackman/zulip,vabs22/zulip,SmartPeople/zulip,kou/zulip,sharmaeklavya2/zulip,JPJPJPOPOP/zulip,peguin40/zulip,peguin40/zulip,dattatreya303/zulip,jainayush975/zulip,TigorC/zulip,zulip/zulip,vabs22/zulip,rht/zulip,zacps/zulip,amanharitsh123/zulip,andersk/zulip,vikas-parashar/zulip,timabbott/zulip,peguin40/zulip,Juanvulcano/zulip,amyliu345/zulip,blaze225/zulip,jackrzhang/zulip,JPJPJPOPOP/zulip,tommyip/zulip,zulip/zulip,dhcrzf/zulip,dattatreya303/zulip,brainwane/zulip,synicalsyntax/zulip,dattatreya303/zulip,sup95/zulip,Galexrt/zulip,dhcrzf/zulip,verma-varsha/zulip,mohsenSy/zulip,rht/zulip,Jianchun1/zulip,ryanbackman/zulip,rht/zulip,jphilipsen05/zulip,brockwhittaker/zulip,aakash-cr7/zulip,punchagan/zulip,hackerkid/zulip,blaze225/zulip,peguin40/zulip,JPJPJPOPOP/zulip,krtkmj/zulip,paxapy/zulip,zulip/zulip,sharmaeklavya2/zulip,ryanbackman/zulip,tommyip/zulip,dawran6/zulip,dawran6/zulip,souravbadami/zulip,christi3k/zulip,kou/zulip,brainwane/zulip,showell/zulip,isht3/zulip,samatdav/zulip,sonali0901/zulip,rishig/zulip,jainayush975/zulip,timabbott/zulip,jphilipsen05/zulip,christi3k/zulip,krtkmj/zulip,timabbott/zulip,ahmadassaf/zulip,vabs22/zulip,shubhamdhama/zulip,brockwhittaker/zulip,ahmadassaf/zulip,rishig/zulip,tommyip/zulip,souravbadami/zulip,verma-varsha/zulip,vaidap/zulip,KingxBanana/zulip,zacps/zulip,dawran6/zulip,andersk/zulip,joyhchen/zulip,susansls/zulip,brainwane/zulip,kou/zulip,cosmicAsymmetry/zulip,SmartPeople/zulip,calvinleenyc/zulip,jrowan/zulip,brainwane/zulip,zulip/zulip,shubhamdhama/zulip,showell/zulip,sonali0901/zulip,hackerkid/zulip,kou/zulip,verma-varsha/zulip,ahmadassaf/zulip,niftynei/zulip,andersk/zulip,showell/zulip,tommyip/zulip,jainayush975/zulip,eeshangarg/zulip,umkay/zulip,vabs22/zulip,verma-varsha/zulip,sup95/zulip,cosmicAsymmetry/zulip,punchagan/zulip,andersk/zulip,jrowan/zulip,jphilipsen05/zulip,synicalsyntax/zulip,joyhchen/zulip,umkay/zulip,rht/zulip,sup95/zulip,vikas-parashar/zulip,rht/zulip,JPJPJPOPOP/zulip,zulip/zulip,jackrzhang/zulip,vaidap/zulip,brainwane/zulip,SmartPeople/zulip,reyha/zulip,reyha/zulip,susansls/zulip,jphilipsen05/zulip,amanharitsh123/zulip,susansls/zulip,tommyip/zulip,calvinleenyc/zulip,j831/zulip,TigorC/zulip,sharmaeklavya2/zulip,Diptanshu8/zulip,isht3/zulip,grave-w-grave/zulip,PhilSk/zulip,umkay/zulip,Galexrt/zulip,samatdav/zulip,christi3k/zulip,amyliu345/zulip,rishig/zulip,KingxBanana/zulip,andersk/zulip,AZtheAsian/zulip,reyha/zulip,j831/zulip,calvinleenyc/zulip,grave-w-grave/zulip,zacps/zulip,blaze225/zulip,reyha/zulip,zulip/zulip,Juanvulcano/zulip,isht3/zulip,synicalsyntax/zulip,isht3/zulip,eeshangarg/zulip,sup95/zulip,punchagan/zulip,isht3/zulip,mahim97/zulip,vaidap/zulip,mahim97/zulip,Juanvulcano/zulip,sonali0901/zulip,kou/zulip,aakash-cr7/zulip,jrowan/zulip,shubhamdhama/zulip,PhilSk/zulip,calvinleenyc/zulip,krtkmj/zulip,showell/zulip,christi3k/zulip,eeshangarg/zulip,paxapy/zulip,tommyip/zulip,timabbott/zulip,ahmadassaf/zulip,dawran6/zulip,zacps/zulip,Galexrt/zulip,ryanbackman/zulip,brockwhittaker/zulip,amyliu345/zulip,mohsenSy/zulip,reyha/zulip,souravbadami/zulip,vaidap/zulip,j831/zulip,krtkmj/zulip,blaze225/zulip,mohsenSy/zulip,paxapy/zulip,paxapy/zulip,vikas-parashar/zulip,dhcrzf/zulip,blaze225/zulip,niftynei/zulip,shubhamdhama/zulip,Jianchun1/zulip,AZtheAsian/zulip,SmartPeople/zulip,AZtheAsian/zulip,mahim97/zulip,umkay/zulip,niftynei/zulip,jainayush975/zulip,vaidap/zulip,peguin40/zulip,TigorC/zulip,grave-w-grave/zulip,rht/zulip,joyhchen/zulip,verma-varsha/zulip,vabs22/zulip,AZtheAsian/zulip,timabbott/zulip,calvinleenyc/zulip,eeshangarg/zulip,calvinleenyc/zulip,sup95/zulip,Diptanshu8/zulip,hackerkid/zulip,krtkmj/zulip,jrowan/zulip,vabs22/zulip,paxapy/zulip,mohsenSy/zulip,susansls/zulip,showell/zulip,eeshangarg/zulip,dhcrzf/zulip,susansls/zulip,dhcrzf/zulip,AZtheAsian/zulip,sup95/zulip,dhcrzf/zulip,aakash-cr7/zulip,PhilSk/zulip,Diptanshu8/zulip,jainayush975/zulip,grave-w-grave/zulip,synicalsyntax/zulip,brockwhittaker/zulip,timabbott/zulip,grave-w-grave/zulip,paxapy/zulip,arpith/zulip,synicalsyntax/zulip,joyhchen/zulip,amyliu345/zulip,jphilipsen05/zulip,SmartPeople/zulip,Diptanshu8/zulip,vikas-parashar/zulip,KingxBanana/zulip,sonali0901/zulip,jackrzhang/zulip,souravbadami/zulip,Juanvulcano/zulip,j831/zulip,Juanvulcano/zulip,rht/zulip,shubhamdhama/zulip,cosmicAsymmetry/zulip,christi3k/zulip,dattatreya303/zulip,mahim97/zulip,arpith/zulip,amyliu345/zulip,samatdav/zulip,zacps/zulip,AZtheAsian/zulip,ahmadassaf/zulip,KingxBanana/zulip,Galexrt/zulip,punchagan/zulip,Jianchun1/zulip,Juanvulcano/zulip,souravbadami/zulip,grave-w-grave/zulip,shubhamdhama/zulip,krtkmj/zulip,rishig/zulip,niftynei/zulip,showell/zulip,jackrzhang/zulip,umkay/zulip,shubhamdhama/zulip,arpith/zulip,hackerkid/zulip,synicalsyntax/zulip,Galexrt/zulip,joyhchen/zulip,brockwhittaker/zulip,JPJPJPOPOP/zulip,KingxBanana/zulip,sharmaeklavya2/zulip,isht3/zulip,verma-varsha/zulip,amanharitsh123/zulip,cosmicAsymmetry/zulip,blaze225/zulip,sharmaeklavya2/zulip,zulip/zulip,christi3k/zulip,samatdav/zulip,punchagan/zulip,arpith/zulip,rishig/zulip,niftynei/zulip