Add "gcl description <change>" subcommand.
Add "gcl description <change>" subcommand.

Prints the multi-line change description.
(Used in forthcoming Emacs gcl integration.)

Review URL: http://codereview.chromium.org/1935002

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@46599 0039d316-1c4b-4281-b951-d872f2087c98

airtimemedia/depot_tools,HackFisher/depot_tools,cybertk/depot_tools,xuyuhan/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,liaorubei/depot_tools,disigma/depot_tools,primiano/depot_tools,G-P-S/depot_tools,G-P-S/depot_tools,kaiix/depot_tools,coreos/depot_tools,airtimemedia/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,coreos/depot_tools,jankeromnes/depot_tools,npe9/depot_tools,withtone/depot_tools,kromain/chromium-tools,liaorubei/depot_tools,eatbyte/depot_tools,mlufei/depot_tools,ajohnson23/depot_tools,hsharsha/depot_tools,npe9/depot_tools,fracting/depot_tools,jankeromnes/depot_tools,SuYiling/chrome_depot_tools,duanwujie/depot_tools,cybertk/depot_tools,disigma/depot_tools,CoherentLabs/depot_tools,xuyuhan/depot_tools,fracting/depot_tools,Chilledheart/depot_tools,sarvex/depot-tools,smikes/depot_tools,npe9/depot_tools,SuYiling/chrome_depot_tools,sarvex/depot-tools,cybertk/depot_tools,Chilledheart/depot_tools,primiano/depot_tools,coreos/depot_tools,michalliu/chromium-depot_tools,liaorubei/depot_tools,HackFisher/depot_tools,yetu/repotools,kromain/chromium-tools,chinmaygarde/depot_tools,withtone/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,gcodetogit/depot_tools,mlufei/depot_tools,Midrya/chromium,aleonliao/depot_tools,gcodetogit/depot_tools,hsharsha/depot_tools,gcodetogit/depot_tools,SuYiling/chrome_depot_tools,chinmaygarde/depot_tools,fanjunwei/depot_tools,ajohnson23/depot_tools,Midrya/chromium,Neozaru/depot_tools,CoherentLabs/depot_tools,smikes/depot_tools,liaorubei/depot_tools,mlufei/depot_tools,Neozaru/depot_tools,G-P-S/depot_tools,cybertk/depot_tools,airtimemedia/depot_tools,hsharsha/depot_tools,aleonliao/depot_tools,airtimemedia/depot_tools,fanjunwei/depot_tools,Phonebooth/depot_tools,jankeromnes/depot_tools,smikes/depot_tools,xuyuhan/depot_tools,sarvex/depot-tools,yetu/repotools,kaiix/depot_tools,kaiix/depot_tools,disigma/depot_tools,G-P-S/depot_tools,primiano/depot_tools,coreos/depot_tools,fanjunwei/depot_tools,eatbyte/depot_tools,fracting/depot_tools,Phonebooth/depot_tools,Phonebooth/depot_tools,Neozaru/depot_tools,Chilledheart/depot_tools,xuyuhan/depot_tools,michalliu/chromium-depot_tools,michalliu/chromium-depot_tools,jankeromnes/depot_tools,eatbyte/depot_tools,azunite/chrome_build,HackFisher/depot_tools,duanwujie/depot_tools,smikes/depot_tools,kromain/chromium-tools,cybertk/depot_tools,jankeromnes/depot_tools,azunite/chrome_build,Neozaru/depot_tools,duongbaoduy/gtools,Phonebooth/depot_tools,coreos/depot_tools,fanjunwei/depot_tools,withtone/depot_tools,smikes/depot_tools,sarvex/depot-tools,Chilledheart/depot_tools,chinmaygarde/depot_tools,Midrya/chromium,duongbaoduy/gtools,Chilledheart/depot_tools,azunite/chrome_build,jankeromnes/depot_tools,ajohnson23/depot_tools,npe9/depot_tools,michalliu/chromium-depot_tools,Neozaru/depot_tools,azureplus/chromium_depot_tools,coreos/depot_tools,jankeromnes/depot_tools,duanwujie/depot_tools,azureplus/chromium_depot_tools,kromain/chromium-tools,aleonliao/depot_tools,duongbaoduy/gtools,yetu/repotools,eatbyte/depot_tools,azureplus/chromium_depot_tools,HackFisher/depot_tools