add a new platform definition for linux
add a new platform definition for linux

On Linux in order for changes made to individual `MenuItem`s to take effect, you have to call `setContextMenu` again

Regarding https://github.com/atom/electron/issues/1473
dongjoon-hyun/electron,dongjoon-hyun/electron,thomsonreuters/electron,biblerule/UMCTelnetHub,rreimann/electron,thomsonreuters/electron,noikiy/electron,gabriel/electron,wan-qy/electron,the-ress/electron,Floato/electron,Gerhut/electron,brave/muon,electron/electron,brave/muon,bpasero/electron,electron/electron,felixrieseberg/electron,brave/electron,Floato/electron,dongjoon-hyun/electron,wan-qy/electron,deed02392/electron,shiftkey/electron,thompsonemerson/electron,thompsonemerson/electron,leethomas/electron,bpasero/electron,bbondy/electron,the-ress/electron,leethomas/electron,miniak/electron,thomsonreuters/electron,preco21/electron,gabriel/electron,wan-qy/electron,rajatsingla28/electron,wan-qy/electron,minggo/electron,noikiy/electron,renaesop/electron,pombredanne/electron,aichingm/electron,felixrieseberg/electron,aliib/electron,bpasero/electron,voidbridge/electron,kcrt/electron,posix4e/electron,jhen0409/electron,felixrieseberg/electron,Gerhut/electron,twolfson/electron,joaomoreno/atom-shell,voidbridge/electron,rreimann/electron,voidbridge/electron,leethomas/electron,electron/electron,miniak/electron,bpasero/electron,gabriel/electron,kokdemo/electron,joaomoreno/atom-shell,felixrieseberg/electron,the-ress/electron,minggo/electron,deed02392/electron,MaxWhere/electron,brenca/electron,renaesop/electron,electron/electron,miniak/electron,tinydew4/electron,posix4e/electron,gerhardberger/electron,electron/electron,MaxWhere/electron,kokdemo/electron,shiftkey/electron,simongregory/electron,seanchas116/electron,jhen0409/electron,aichingm/electron,simongregory/electron,bbondy/electron,preco21/electron,brave/muon,kokdemo/electron,aichingm/electron,shiftkey/electron,rreimann/electron,the-ress/electron,rajatsingla28/electron,stevekinney/electron,Gerhut/electron,thompsonemerson/electron,joaomoreno/atom-shell,voidbridge/electron,brave/electron,deed02392/electron,gerhardberger/electron,tinydew4/electron,gabriel/electron,preco21/electron,minggo/electron,rajatsingla28/electron,MaxWhere/electron,minggo/electron,renaesop/electron,Floato/electron,aichingm/electron,bpasero/electron,Floato/electron,brenca/electron,seanchas116/electron,wan-qy/electron,bbondy/electron,aliib/electron,stevekinney/electron,kcrt/electron,gerhardberger/electron,MaxWhere/electron,gerhardberger/electron,deed02392/electron,aichingm/electron,leethomas/electron,deed02392/electron,gerhardberger/electron,stevekinney/electron,the-ress/electron,brenca/electron,seanchas116/electron,tonyganch/electron,noikiy/electron,gerhardberger/electron,shiftkey/electron,joaomoreno/atom-shell,seanchas116/electron,dongjoon-hyun/electron,biblerule/UMCTelnetHub,Gerhut/electron,deed02392/electron,gerhardberger/electron,bpasero/electron,voidbridge/electron,gabriel/electron,electron/electron,shiftkey/electron,miniak/electron,pombredanne/electron,rajatsingla28/electron,tinydew4/electron,tonyganch/electron,tonyganch/electron,jhen0409/electron,felixrieseberg/electron,rreimann/electron,noikiy/electron,kcrt/electron,wan-qy/electron,pombredanne/electron,preco21/electron,twolfson/electron,aichingm/electron,leethomas/electron,twolfson/electron,bbondy/electron,aliib/electron,kcrt/electron,joaomoreno/atom-shell,brenca/electron,tinydew4/electron,brenca/electron,rreimann/electron,thompsonemerson/electron,posix4e/electron,preco21/electron,thompsonemerson/electron,jhen0409/electron,brave/muon,renaesop/electron,MaxWhere/electron,pombredanne/electron,biblerule/UMCTelnetHub,tonyganch/electron,twolfson/electron,posix4e/electron,miniak/electron,bbondy/electron,kcrt/electron,renaesop/electron,preco21/electron,stevekinney/electron,biblerule/UMCTelnetHub,twolfson/electron,leethomas/electron,posix4e/electron,simongregory/electron,simongregory/electron,rajatsingla28/electron,voidbridge/electron,the-ress/electron,kokdemo/electron,Gerhut/electron,kokdemo/electron,pombredanne/electron,brenca/electron,posix4e/electron,felixrieseberg/electron,joaomoreno/atom-shell,electron/electron,Floato/electron,thompsonemerson/electron,tonyganch/electron,minggo/electron,thomsonreuters/electron,seanchas116/electron,thomsonreuters/electron,the-ress/electron,twolfson/electron,stevekinney/electron,aliib/electron,miniak/electron,stevekinney/electron,Floato/electron,dongjoon-hyun/electron,brave/electron,MaxWhere/electron,thomsonreuters/electron,simongregory/electron,biblerule/UMCTelnetHub,kcrt/electron,renaesop/electron,jhen0409/electron,pombredanne/electron,tonyganch/electron,dongjoon-hyun/electron,seanchas116/electron,tinydew4/electron,brave/electron,noikiy/electron,rreimann/electron,noikiy/electron,tinydew4/electron,bpasero/electron,biblerule/UMCTelnetHub,brave/muon,kokdemo/electron,jhen0409/electron,bbondy/electron,shiftkey/electron,minggo/electron,Gerhut/electron,brave/muon,aliib/electron,brave/electron,aliib/electron,gabriel/electron,brave/electron,simongregory/electron,rajatsingla28/electron