[Tools] fetch_deps: Call sys.exit() only at the very end.
[Tools] fetch_deps: Call sys.exit() only at the very end.

Stop making main() sometimes just return a value and sometimes exit()ing
directly: standardize on calling sys.exit() with main()s return for
consistency and also to accommodate adding calls to more DepsFetcher
methods in the future.

tomatell/crosswalk,Pluto-tv/crosswalk,minggangw/crosswalk,chinakids/crosswalk,hgl888/crosswalk-efl,zeropool/crosswalk,tedshroyer/crosswalk,Bysmyyr/crosswalk,jondwillis/crosswalk,lincsoon/crosswalk,xzhan96/crosswalk,bestwpw/crosswalk,myroot/crosswalk,ZhengXinCN/crosswalk,Bysmyyr/crosswalk,rakuco/crosswalk,axinging/crosswalk,marcuspridham/crosswalk,rakuco/crosswalk,XiaosongWei/crosswalk,crosswalk-project/crosswalk-efl,tomatell/crosswalk,weiyirong/crosswalk-1,amaniak/crosswalk,pk-sam/crosswalk,crosswalk-project/crosswalk-efl,crosswalk-project/crosswalk,baleboy/crosswalk,alex-zhang/crosswalk,Bysmyyr/crosswalk,qjia7/crosswalk,marcuspridham/crosswalk,stonegithubs/crosswalk,bestwpw/crosswalk,darktears/crosswalk,pk-sam/crosswalk,minggangw/crosswalk,shaochangbin/crosswalk,qjia7/crosswalk,chinakids/crosswalk,zliang7/crosswalk,zliang7/crosswalk,crosswalk-project/crosswalk,leonhsl/crosswalk,leonhsl/crosswalk,PeterWangIntel/crosswalk,crosswalk-project/crosswalk,chuan9/crosswalk,chuan9/crosswalk,shaochangbin/crosswalk,dreamsxin/crosswalk,tomatell/crosswalk,myroot/crosswalk,leonhsl/crosswalk,RafuCater/crosswalk,pk-sam/crosswalk,zeropool/crosswalk,hgl888/crosswalk-efl,XiaosongWei/crosswalk,crosswalk-project/crosswalk,baleboy/crosswalk,hgl888/crosswalk,darktears/crosswalk,huningxin/crosswalk,zliang7/crosswalk,hgl888/crosswalk,bestwpw/crosswalk,weiyirong/crosswalk-1,jondong/crosswalk,crosswalk-project/crosswalk-efl,Bysmyyr/crosswalk,jondong/crosswalk,jpike88/crosswalk,amaniak/crosswalk,weiyirong/crosswalk-1,zeropool/crosswalk,siovene/crosswalk,minggangw/crosswalk,axinging/crosswalk,Bysmyyr/crosswalk,PeterWangIntel/crosswalk,leonhsl/crosswalk,crosswalk-project/crosswalk,baleboy/crosswalk,fujunwei/crosswalk,RafuCater/crosswalk,pk-sam/crosswalk,amaniak/crosswalk,XiaosongWei/crosswalk,crosswalk-project/crosswalk-efl,chinakids/crosswalk,shaochangbin/crosswalk,marcuspridham/crosswalk,TheDirtyCalvinist/spacewalk,jondong/crosswalk,zliang7/crosswalk,huningxin/crosswalk,heke123/crosswalk,chuan9/crosswalk,baleboy/crosswalk,chuan9/crosswalk,zliang7/crosswalk,Pluto-tv/crosswalk,darktears/crosswalk,Bysmyyr/crosswalk,xzhan96/crosswalk,hgl888/crosswalk-efl,heke123/crosswalk,lincsoon/crosswalk,zeropool/crosswalk,heke123/crosswalk,pk-sam/crosswalk,DonnaWuDongxia/crosswalk,baleboy/crosswalk,marcuspridham/crosswalk,bestwpw/crosswalk,mrunalk/crosswalk,minggangw/crosswalk,alex-zhang/crosswalk,siovene/crosswalk,jpike88/crosswalk,RafuCater/crosswalk,ZhengXinCN/crosswalk,dreamsxin/crosswalk,crosswalk-project/crosswalk,fujunwei/crosswalk,weiyirong/crosswalk-1,jondong/crosswalk,tomatell/crosswalk,hgl888/crosswalk,heke123/crosswalk,mrunalk/crosswalk,jpike88/crosswalk,hgl888/crosswalk-efl,weiyirong/crosswalk-1,baleboy/crosswalk,jondong/crosswalk,lincsoon/crosswalk,hgl888/crosswalk-efl,rakuco/crosswalk,xzhan96/crosswalk,RafuCater/crosswalk,myroot/crosswalk,rakuco/crosswalk,RafuCater/crosswalk,amaniak/crosswalk,XiaosongWei/crosswalk,chinakids/crosswalk,lincsoon/crosswalk,jondwillis/crosswalk,rakuco/crosswalk,dreamsxin/crosswalk,myroot/crosswalk,marcuspridham/crosswalk,crosswalk-project/crosswalk-efl,axinging/crosswalk,Bysmyyr/crosswalk,chuan9/crosswalk,myroot/crosswalk,lincsoon/crosswalk,amaniak/crosswalk,stonegithubs/crosswalk,alex-zhang/crosswalk,fujunwei/crosswalk,dreamsxin/crosswalk,axinging/crosswalk,shaochangbin/crosswalk,huningxin/crosswalk,xzhan96/crosswalk,Pluto-tv/crosswalk,amaniak/crosswalk,myroot/crosswalk,weiyirong/crosswalk-1,Pluto-tv/crosswalk,mrunalk/crosswalk,tedshroyer/crosswalk,XiaosongWei/crosswalk,jondong/crosswalk,Pluto-tv/crosswalk,rakuco/crosswalk,ZhengXinCN/crosswalk,baleboy/crosswalk,tedshroyer/crosswalk,hgl888/crosswalk-efl,jondong/crosswalk,fujunwei/crosswalk,ZhengXinCN/crosswalk,ZhengXinCN/crosswalk,zliang7/crosswalk,dreamsxin/crosswalk,heke123/crosswalk,jondwillis/crosswalk,huningxin/crosswalk,marcuspridham/crosswalk,minggangw/crosswalk,DonnaWuDongxia/crosswalk,DonnaWuDongxia/crosswalk,stonegithubs/crosswalk,fujunwei/crosswalk,mrunalk/crosswalk,fujunwei/crosswalk,lincsoon/crosswalk,tomatell/crosswalk,heke123/crosswalk,pk-sam/crosswalk,shaochangbin/crosswalk,heke123/crosswalk,TheDirtyCalvinist/spacewalk,PeterWangIntel/crosswalk,bestwpw/crosswalk,weiyirong/crosswalk-1,jpike88/crosswalk,tedshroyer/crosswalk,alex-zhang/crosswalk,jpike88/crosswalk,TheDirtyCalvinist/spacewalk,minggangw/crosswalk,chuan9/crosswalk,stonegithubs/crosswalk,DonnaWuDongxia/crosswalk,chuan9/crosswalk,bestwpw/crosswalk,chinakids/crosswalk,heke123/crosswalk,stonegithubs/crosswalk,marcuspridham/crosswalk,qjia7/crosswalk,xzhan96/crosswalk,Bysmyyr/crosswalk,rakuco/crosswalk,stonegithubs/crosswalk,zeropool/crosswalk,stonegithubs/crosswalk,leonhsl/crosswalk,siovene/crosswalk,jondong/crosswalk,lincsoon/crosswalk,Pluto-tv/crosswalk,XiaosongWei/crosswalk,jpike88/crosswalk,RafuCater/crosswalk,ZhengXinCN/crosswalk,tedshroyer/crosswalk,ZhengXinCN/crosswalk,axinging/crosswalk,hgl888/crosswalk,bestwpw/crosswalk,dreamsxin/crosswalk,shaochangbin/crosswalk,DonnaWuDongxia/crosswalk,siovene/crosswalk,rakuco/crosswalk,crosswalk-project/crosswalk,hgl888/crosswalk,amaniak/crosswalk,siovene/crosswalk,huningxin/crosswalk,siovene/crosswalk,siovene/crosswalk,darktears/crosswalk,alex-zhang/crosswalk,huningxin/crosswalk,hgl888/crosswalk,Pluto-tv/crosswalk,DonnaWuDongxia/crosswalk,zeropool/crosswalk,hgl888/crosswalk-efl,mrunalk/crosswalk,xzhan96/crosswalk,PeterWangIntel/crosswalk,TheDirtyCalvinist/spacewalk,tomatell/crosswalk,jpike88/crosswalk,qjia7/crosswalk,hgl888/crosswalk,chinakids/crosswalk,TheDirtyCalvinist/spacewalk,XiaosongWei/crosswalk,darktears/crosswalk,tomatell/crosswalk,zliang7/crosswalk,darktears/crosswalk,xzhan96/crosswalk,dreamsxin/crosswalk,RafuCater/crosswalk,PeterWangIntel/crosswalk,leonhsl/crosswalk,jondwillis/crosswalk,DonnaWuDongxia/crosswalk,crosswalk-project/crosswalk-efl,mrunalk/crosswalk,jondwillis/crosswalk,baleboy/crosswalk,fujunwei/crosswalk,alex-zhang/crosswalk,alex-zhang/crosswalk,axinging/crosswalk,PeterWangIntel/crosswalk,hgl888/crosswalk,pk-sam/crosswalk,TheDirtyCalvinist/spacewalk,xzhan96/crosswalk,zeropool/crosswalk,leonhsl/crosswalk,lincsoon/crosswalk,crosswalk-project/crosswalk,jondwillis/crosswalk,tedshroyer/crosswalk,qjia7/crosswalk,jondwillis/crosswalk,minggangw/crosswalk,darktears/crosswalk,minggangw/crosswalk,qjia7/crosswalk,darktears/crosswalk,tedshroyer/crosswalk,crosswalk-project/crosswalk-efl,marcuspridham/crosswalk,zliang7/crosswalk,PeterWangIntel/crosswalk,axinging/crosswalk