poco: Fix the build on Linux
poco: Fix the build on Linux

Closes Homebrew/linuxbrew#98

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