[build-script] Create 'buildbot_linux' preset to reduce duplication
[build-script] Create 'buildbot_linux' preset to reduce duplication

The Ubuntu 14.04 preset existed to skip building Foundation due to
unavailable ICU versions. The problem was corrected, but the
comment and preset duplication of 'buildbot_linux_*' in
build-presets.ini remained.

This change adds a 'buildbot_linux' preset as the primary Linux
preset and changes 'buildbot_linux_*' to use it as a mixin.

Implemented as discussed with Dmitri Gribenko on swift-dev.

ben-ng/swift,devincoughlin/swift,alblue/swift,ahoppen/swift,gottesmm/swift,therealbnut/swift,JaSpa/swift,arvedviehweger/swift,jmgc/swift,ken0nek/swift,felix91gr/swift,Jnosh/swift,tkremenek/swift,ben-ng/swift,huonw/swift,nathawes/swift,tkremenek/swift,IngmarStein/swift,tjw/swift,gmilos/swift,arvedviehweger/swift,uasys/swift,gmilos/swift,airspeedswift/swift,gregomni/swift,therealbnut/swift,xwu/swift,lorentey/swift,manavgabhawala/swift,huonw/swift,karwa/swift,OscarSwanros/swift,brentdax/swift,codestergit/swift,uasys/swift,austinzheng/swift,modocache/swift,xwu/swift,bitjammer/swift,gribozavr/swift,airspeedswift/swift,rudkx/swift,johnno1962d/swift,shahmishal/swift,xedin/swift,dduan/swift,harlanhaskins/swift,gottesmm/swift,calebd/swift,practicalswift/swift,tardieu/swift,IngmarStein/swift,tkremenek/swift,rudkx/swift,modocache/swift,sschiau/swift,frootloops/swift,xwu/swift,return/swift,shahmishal/swift,gmilos/swift,aschwaighofer/swift,djwbrown/swift,IngmarStein/swift,lorentey/swift,sschiau/swift,djwbrown/swift,felix91gr/swift,JaSpa/swift,parkera/swift,swiftix/swift,SwiftAndroid/swift,adrfer/swift,stephentyrone/swift,manavgabhawala/swift,jtbandes/swift,uasys/swift,amraboelela/swift,CodaFi/swift,jtbandes/swift,Jnosh/swift,tardieu/swift,kstaring/swift,atrick/swift,jopamer/swift,airspeedswift/swift,gregomni/swift,jmgc/swift,hooman/swift,nathawes/swift,Jnosh/swift,tinysun212/swift-windows,JaSpa/swift,xedin/swift,benlangmuir/swift,frootloops/swift,dreamsxin/swift,sschiau/swift,allevato/swift,jopamer/swift,harlanhaskins/swift,airspeedswift/swift,kperryua/swift,lorentey/swift,danielmartin/swift,IngmarStein/swift,roambotics/swift,shahmishal/swift,ken0nek/swift,deyton/swift,return/swift,huonw/swift,therealbnut/swift,felix91gr/swift,natecook1000/swift,nathawes/swift,stephentyrone/swift,danielmartin/swift,practicalswift/swift,zisko/swift,return/swift,stephentyrone/swift,alblue/swift,SwiftAndroid/swift,sschiau/swift,codestergit/swift,rudkx/swift,devincoughlin/swift,SwiftAndroid/swift,JGiola/swift,hughbe/swift,russbishop/swift,hooman/swift,allevato/swift,milseman/swift,ahoppen/swift,gribozavr/swift,shajrawi/swift,harlanhaskins/swift,codestergit/swift,brentdax/swift,natecook1000/swift,gottesmm/swift,jtbandes/swift,calebd/swift,therealbnut/swift,modocache/swift,kperryua/swift,johnno1962d/swift,djwbrown/swift,brentdax/swift,nathawes/swift,CodaFi/swift,OscarSwanros/swift,rudkx/swift,karwa/swift,ben-ng/swift,manavgabhawala/swift,gottesmm/swift,shajrawi/swift,KrishMunot/swift,adrfer/swift,return/swift,Jnosh/swift,danielmartin/swift,arvedviehweger/swift,felix91gr/swift,therealbnut/swift,shajrawi/swift,modocache/swift,hughbe/swift,russbishop/swift,austinzheng/swift,zisko/swift,gribozavr/swift,codestergit/swift,practicalswift/swift,jopamer/swift,milseman/swift,kstaring/swift,swiftix/swift,natecook1000/swift,bitjammer/swift,adrfer/swift,jmgc/swift,MukeshKumarS/Swift,manavgabhawala/swift,kstaring/swift,lorentey/swift,gregomni/swift,johnno1962d/swift,MukeshKumarS/Swift,CodaFi/swift,nathawes/swift,xedin/swift,KrishMunot/swift,SwiftAndroid/swift,hughbe/swift,allevato/swift,brentdax/swift,parkera/swift,djwbrown/swift,karwa/swift,slavapestov/swift,tardieu/swift,atrick/swift,harlanhaskins/swift,tardieu/swift,zisko/swift,hooman/swift,ahoppen/swift,amraboelela/swift,lorentey/swift,kstaring/swift,practicalswift/swift,tkremenek/swift,jckarter/swift,KrishMunot/swift,calebd/swift,SwiftAndroid/swift,aschwaighofer/swift,JGiola/swift,rudkx/swift,tjw/swift,bitjammer/swift,aschwaighofer/swift,MukeshKumarS/Swift,devincoughlin/swift,milseman/swift,JGiola/swift,tardieu/swift,hooman/swift,modocache/swift,return/swift,arvedviehweger/swift,zisko/swift,OscarSwanros/swift,frootloops/swift,OscarSwanros/swift,shahmishal/swift,atrick/swift,aschwaighofer/swift,uasys/swift,benlangmuir/swift,jckarter/swift,Jnosh/swift,arvedviehweger/swift,uasys/swift,devincoughlin/swift,gmilos/swift,huonw/swift,johnno1962d/swift,shajrawi/swift,JaSpa/swift,roambotics/swift,calebd/swift,airspeedswift/swift,karwa/swift,calebd/swift,frootloops/swift,calebd/swift,JaSpa/swift,MukeshKumarS/Swift,danielmartin/swift,austinzheng/swift,ben-ng/swift,jopamer/swift,practicalswift/swift,ken0nek/swift,JaSpa/swift,practicalswift/swift,alblue/swift,amraboelela/swift,brentdax/swift,apple/swift,JGiola/swift,codestergit/swift,hooman/swift,shajrawi/swift,sschiau/swift,slavapestov/swift,airspeedswift/swift,bitjammer/swift,codestergit/swift,OscarSwanros/swift,sschiau/swift,amraboelela/swift,deyton/swift,MukeshKumarS/Swift,deyton/swift,benlangmuir/swift,jopamer/swift,gottesmm/swift,CodaFi/swift,xwu/swift,milseman/swift,felix91gr/swift,airspeedswift/swift,JaSpa/swift,shajrawi/swift,gottesmm/swift,amraboelela/swift,xedin/swift,danielmartin/swift,djwbrown/swift,deyton/swift,tinysun212/swift-windows,stephentyrone/swift,jopamer/swift,jtbandes/swift,return/swift,sschiau/swift,sschiau/swift,swiftix/swift,djwbrown/swift,OscarSwanros/swift,ken0nek/swift,return/swift,KrishMunot/swift,felix91gr/swift,deyton/swift,shajrawi/swift,roambotics/swift,Jnosh/swift,adrfer/swift,hughbe/swift,roambotics/swift,natecook1000/swift,deyton/swift,aschwaighofer/swift,jmgc/swift,benlangmuir/swift,russbishop/swift,rudkx/swift,amraboelela/swift,hughbe/swift,lorentey/swift,jmgc/swift,natecook1000/swift,gregomni/swift,tkremenek/swift,tinysun212/swift-windows,stephentyrone/swift,hughbe/swift,jopamer/swift,allevato/swift,swiftix/swift,johnno1962d/swift,devincoughlin/swift,ben-ng/swift,atrick/swift,roambotics/swift,apple/swift,therealbnut/swift,russbishop/swift,xedin/swift,nathawes/swift,xwu/swift,djwbrown/swift,adrfer/swift,allevato/swift,kstaring/swift,gribozavr/swift,johnno1962d/swift,gmilos/swift,slavapestov/swift,CodaFi/swift,gribozavr/swift,jckarter/swift,modocache/swift,austinzheng/swift,milseman/swift,zisko/swift,parkera/swift,shahmishal/swift,harlanhaskins/swift,gmilos/swift,devincoughlin/swift,manavgabhawala/swift,SwiftAndroid/swift,tjw/swift,ahoppen/swift,dduan/swift,brentdax/swift,frootloops/swift,MukeshKumarS/Swift,brentdax/swift,practicalswift/swift,tardieu/swift,dduan/swift,austinzheng/swift,parkera/swift,huonw/swift,huonw/swift,slavapestov/swift,danielmartin/swift,hooman/swift,apple/swift,tjw/swift,glessard/swift,ahoppen/swift,kperryua/swift,JGiola/swift,natecook1000/swift,bitjammer/swift,adrfer/swift,slavapestov/swift,kperryua/swift,zisko/swift,jmgc/swift,apple/swift,aschwaighofer/swift,IngmarStein/swift,therealbnut/swift,xedin/swift,KrishMunot/swift,manavgabhawala/swift,dreamsxin/swift,alblue/swift,MukeshKumarS/Swift,calebd/swift,jckarter/swift,aschwaighofer/swift,parkera/swift,JGiola/swift,slavapestov/swift,harlanhaskins/swift,SwiftAndroid/swift,karwa/swift,danielmartin/swift,glessard/swift,tkremenek/swift,shahmishal/swift,harlanhaskins/swift,russbishop/swift,apple/swift,swiftix/swift,allevato/swift,gmilos/swift,zisko/swift,gribozavr/swift,jmgc/swift,alblue/swift,xwu/swift,tinysun212/swift-windows,ahoppen/swift,gregomni/swift,huonw/swift,kstaring/swift,jckarter/swift,hooman/swift,jtbandes/swift,tjw/swift,shajrawi/swift,johnno1962d/swift,xedin/swift,modocache/swift,Jnosh/swift,atrick/swift,kperryua/swift,dduan/swift,benlangmuir/swift,lorentey/swift,kperryua/swift,deyton/swift,dduan/swift,parkera/swift,roambotics/swift,ken0nek/swift,glessard/swift,gregomni/swift,nathawes/swift,adrfer/swift,arvedviehweger/swift,dduan/swift,glessard/swift,KrishMunot/swift,swiftix/swift,parkera/swift,russbishop/swift,tjw/swift,kstaring/swift,karwa/swift,swiftix/swift,devincoughlin/swift,frootloops/swift,tjw/swift,xedin/swift,hughbe/swift,tinysun212/swift-windows,karwa/swift,alblue/swift,jtbandes/swift,frootloops/swift,gottesmm/swift,dduan/swift,jtbandes/swift,stephentyrone/swift,manavgabhawala/swift,uasys/swift,jckarter/swift,austinzheng/swift,ken0nek/swift,codestergit/swift,xwu/swift,stephentyrone/swift,gribozavr/swift,shahmishal/swift,tkremenek/swift,shahmishal/swift,glessard/swift,allevato/swift,atrick/swift,glessard/swift,amraboelela/swift,lorentey/swift,jckarter/swift,bitjammer/swift,bitjammer/swift,gribozavr/swift,IngmarStein/swift,kperryua/swift,tinysun212/swift-windows,tinysun212/swift-windows,OscarSwanros/swift,parkera/swift,IngmarStein/swift,uasys/swift,milseman/swift,devincoughlin/swift,CodaFi/swift,CodaFi/swift,natecook1000/swift,practicalswift/swift,karwa/swift,milseman/swift,KrishMunot/swift,apple/swift,ben-ng/swift,russbishop/swift,arvedviehweger/swift,felix91gr/swift,slavapestov/swift,ken0nek/swift,tardieu/swift,benlangmuir/swift,austinzheng/swift,alblue/swift,ben-ng/swift