Linuxbrew: Fix --env=inherit
Linuxbrew: Fix --env=inherit

Fix checks for gcc compiler when not present and --env=inherit specified.
Fixes Homebrew/linuxbrew#136
See chapmanb/bcbio-nextgen#604
See chapmanb/bcbio-nextgen#605
See chapmanb/bcbio-nextgen#606

DoomHammer/linuxbrew,oneillkza/linuxbrew,tomas/linuxbrew,bukzor/linuxbrew,gcstang/linuxbrew,davydden/linuxbrew,tomas/linuxbrew,brendanator/linuxbrew,danabrand/linuxbrew,cbeck88/linuxbrew,Angeldude/linuxbrew,10sr/linuxbrew,jwillemsen/linuxbrew,jwillemsen/linuxbrew,sublimino/linuxbrew,Gui13/linuxbrew,amenk/linuxbrew,gnubila-france/linuxbrew,trskop/linuxbrew,sjackman/linuxbrew,gnubila-france/linuxbrew,brendanator/linuxbrew,brevilo/linuxbrew,romejoe/linuxbrew,jbaum98/linuxbrew,oneillkza/linuxbrew,tdsmith/linuxbrew,tdsmith/linuxbrew,sarvex/linuxbrew,Gui13/linuxbrew,trskop/linuxbrew,Homebrew/linuxbrew,SuperNEMO-DBD/cadfaelbrew,bukzor/linuxbrew,princeofdarkness76/linuxbrew,ebouaziz/linuxbrew,tdsmith/linuxbrew,ebouaziz/linuxbrew,saketkc/linuxbrew,jlisic/linuxbrew,dholm/linuxbrew,trskop/linuxbrew,danabrand/linuxbrew,telamonian/linuxbrew,digiter/linuxbrew,jbaum98/linuxbrew,dunn/linuxbrew,afdnlw/linuxbrew,jack-and-rozz/linuxbrew,Linuxbrew/linuxbrew,winordie-47/linuxbrew1,gnubila-france/linuxbrew,tdsmith/linuxbrew,cbeck88/linuxbrew,tomas/linuxbrew,sjackman/linuxbrew,amenk/linuxbrew,adamliter/linuxbrew,jlisic/linuxbrew,amenk/linuxbrew,digiter/linuxbrew,ebouaziz/linuxbrew,tbetbetbe/linuxbrew,jwillemsen/linuxbrew,tbetbetbe/linuxbrew,oneillkza/linuxbrew,brendanator/linuxbrew,Gui13/linuxbrew,tbetbetbe/linuxbrew,brevilo/linuxbrew,jack-and-rozz/linuxbrew,iggyvolz/linuxbrew,drbenmorgan/linuxbrew,dunn/linuxbrew,jlisic/linuxbrew,sarvex/linuxbrew,SuperNEMO-DBD/cadfaelbrew,tghs/linuxbrew,Linuxbrew/linuxbrew,sublimino/linuxbrew,sarvex/linuxbrew,bukzor/linuxbrew,davydden/linuxbrew,lvicentesanchez/linuxbrew,tomas/linuxbrew,dunn/linuxbrew,IsmailM/linuxbrew,sublimino/linuxbrew,afdnlw/linuxbrew,reelsense/linuxbrew,telamonian/linuxbrew,lvicentesanchez/linuxbrew,tghs/linuxbrew,adamliter/linuxbrew,arcivanov/linuxbrew,digiter/linuxbrew,dunn/linuxbrew,winordie-47/linuxbrew1,telamonian/linuxbrew,afdnlw/linuxbrew,davydden/linuxbrew,tjhei/linuxbrew,reelsense/linuxbrew,sarvex/linuxbrew,caputomarcos/linuxbrew,DoomHammer/linuxbrew,tghs/linuxbrew,cbeck88/linuxbrew,sjackman/linuxbrew,jack-and-rozz/linuxbrew,jbaum98/linuxbrew,reelsense/linuxbrew,IsmailM/linuxbrew,hyokosdeveloper/linuxbrew,adamliter/linuxbrew,tjhei/linuxbrew,romejoe/linuxbrew,SuperNEMO-DBD/cadfaelbrew,afdnlw/linuxbrew,princeofdarkness76/linuxbrew,davydden/linuxbrew,winordie-47/linuxbrew1,winordie-47/linuxbrew1,tjhei/linuxbrew,Angeldude/linuxbrew,caputomarcos/linuxbrew,10sr/linuxbrew,iggyvolz/linuxbrew,SuperNEMO-DBD/cadfaelbrew,ebouaziz/linuxbrew,drbenmorgan/linuxbrew,gcstang/linuxbrew,Homebrew/linuxbrew,hyokosdeveloper/linuxbrew,dholm/linuxbrew,Angeldude/linuxbrew,DoomHammer/linuxbrew,gcstang/linuxbrew,reelsense/linuxbrew,IsmailM/linuxbrew,jbaum98/linuxbrew,gnubila-france/linuxbrew,tbetbetbe/linuxbrew,sublimino/linuxbrew,drbenmorgan/linuxbrew,arcivanov/linuxbrew,bukzor/linuxbrew,IsmailM/linuxbrew,Linuxbrew/linuxbrew,Gui13/linuxbrew,saketkc/linuxbrew,brevilo/linuxbrew,DoomHammer/linuxbrew,lvicentesanchez/linuxbrew,digiter/linuxbrew,sjackman/linuxbrew,outcoldman/linuxbrew,caputomarcos/linuxbrew,Homebrew/linuxbrew,digiter/linuxbrew,outcoldman/linuxbrew,lvicentesanchez/linuxbrew,LeonB/linuxbrew,Gui13/linuxbrew,Angeldude/linuxbrew,adamliter/linuxbrew,hyokosdeveloper/linuxbrew,Homebrew/linuxbrew,caputomarcos/linuxbrew,tghs/linuxbrew,dholm/linuxbrew,outcoldman/linuxbrew,amenk/linuxbrew,arcivanov/linuxbrew,LeonB/linuxbrew,saketkc/linuxbrew,iggyvolz/linuxbrew,10sr/linuxbrew,Linuxbrew/linuxbrew,tdsmith/linuxbrew,LeonB/linuxbrew,romejoe/linuxbrew,danabrand/linuxbrew,hyokosdeveloper/linuxbrew,drbenmorgan/linuxbrew,tghs/linuxbrew,saketkc/linuxbrew,princeofdarkness76/linuxbrew,danabrand/linuxbrew,oneillkza/linuxbrew