README: Clean up references to CMake and Ninja on OS X
README: Clean up references to CMake and Ninja on OS X

- Add instructions for installing these on OS X
- Clean up the build-script section

benlangmuir/swift,gmilos/swift,Jnosh/swift,stephentyrone/swift,lorentey/swift,lorentey/swift,karwa/swift,OscarSwanros/swift,kusl/swift,adrfer/swift,shahmishal/swift,jtbandes/swift,huonw/swift,arvedviehweger/swift,stephentyrone/swift,practicalswift/swift,ken0nek/swift,shajrawi/swift,bitjammer/swift,emilstahl/swift,xwu/swift,therealbnut/swift,xwu/swift,LeoShimonaka/swift,swiftix/swift.old,nathawes/swift,cbrentharris/swift,CodaFi/swift,tardieu/swift,tkremenek/swift,Ivacker/swift,frootloops/swift,cbrentharris/swift,kentya6/swift,slavapestov/swift,Ivacker/swift,glessard/swift,amraboelela/swift,felix91gr/swift,emilstahl/swift,djwbrown/swift,roambotics/swift,johnno1962d/swift,adrfer/swift,OscarSwanros/swift,brentdax/swift,khizkhiz/swift,arvedviehweger/swift,sdulal/swift,deyton/swift,JaSpa/swift,tardieu/swift,dduan/swift,karwa/swift,apple/swift,swiftix/swift.old,uasys/swift,adrfer/swift,danielmartin/swift,sschiau/swift,MukeshKumarS/Swift,frootloops/swift,gmilos/swift,atrick/swift,gmilos/swift,SwiftAndroid/swift,harlanhaskins/swift,milseman/swift,glessard/swift,gottesmm/swift,gribozavr/swift,austinzheng/swift,kperryua/swift,modocache/swift,tkremenek/swift,sdulal/swift,tkremenek/swift,johnno1962d/swift,xedin/swift,tkremenek/swift,benlangmuir/swift,gottesmm/swift,huonw/swift,sschiau/swift,danielmartin/swift,khizkhiz/swift,adrfer/swift,shajrawi/swift,harlanhaskins/swift,xedin/swift,modocache/swift,amraboelela/swift,gribozavr/swift,jmgc/swift,shajrawi/swift,MukeshKumarS/Swift,SwiftAndroid/swift,codestergit/swift,russbishop/swift,lorentey/swift,gottesmm/swift,roambotics/swift,OscarSwanros/swift,gregomni/swift,sdulal/swift,therealbnut/swift,kstaring/swift,codestergit/swift,austinzheng/swift,devincoughlin/swift,huonw/swift,austinzheng/swift,zisko/swift,roambotics/swift,Ivacker/swift,tjw/swift,IngmarStein/swift,milseman/swift,russbishop/swift,tardieu/swift,natecook1000/swift,dduan/swift,gribozavr/swift,benlangmuir/swift,JGiola/swift,jckarter/swift,Jnosh/swift,swiftix/swift.old,kperryua/swift,manavgabhawala/swift,parkera/swift,OscarSwanros/swift,Jnosh/swift,sschiau/swift,xwu/swift,jmgc/swift,xwu/swift,jmgc/swift,nathawes/swift,hooman/swift,danielmartin/swift,russbishop/swift,JGiola/swift,JaSpa/swift,johnno1962d/swift,tkremenek/swift,parkera/swift,jmgc/swift,mightydeveloper/swift,shahmishal/swift,ben-ng/swift,xedin/swift,shajrawi/swift,khizkhiz/swift,IngmarStein/swift,kperryua/swift,uasys/swift,austinzheng/swift,dduan/swift,hughbe/swift,alblue/swift,benlangmuir/swift,apple/swift,gottesmm/swift,LeoShimonaka/swift,karwa/swift,mightydeveloper/swift,allevato/swift,zisko/swift,KrishMunot/swift,gribozavr/swift,hooman/swift,practicalswift/swift,kstaring/swift,zisko/swift,hooman/swift,rudkx/swift,deyton/swift,devincoughlin/swift,kperryua/swift,kentya6/swift,slavapestov/swift,kentya6/swift,IngmarStein/swift,jckarter/swift,djwbrown/swift,manavgabhawala/swift,cbrentharris/swift,huonw/swift,djwbrown/swift,bitjammer/swift,nathawes/swift,kperryua/swift,glessard/swift,glessard/swift,SwiftAndroid/swift,return/swift,parkera/swift,uasys/swift,airspeedswift/swift,dduan/swift,IngmarStein/swift,stephentyrone/swift,milseman/swift,SwiftAndroid/swift,glessard/swift,therealbnut/swift,airspeedswift/swift,emilstahl/swift,kperryua/swift,jtbandes/swift,harlanhaskins/swift,Jnosh/swift,mightydeveloper/swift,rudkx/swift,apple/swift,calebd/swift,emilstahl/swift,huonw/swift,Ivacker/swift,ken0nek/swift,devincoughlin/swift,shajrawi/swift,practicalswift/swift,CodaFi/swift,khizkhiz/swift,tkremenek/swift,practicalswift/swift,jckarter/swift,kentya6/swift,Jnosh/swift,deyton/swift,frootloops/swift,Ivacker/swift,austinzheng/swift,jmgc/swift,jtbandes/swift,uasys/swift,manavgabhawala/swift,gottesmm/swift,ben-ng/swift,return/swift,roambotics/swift,dduan/swift,devincoughlin/swift,CodaFi/swift,mightydeveloper/swift,gribozavr/swift,djwbrown/swift,KrishMunot/swift,emilstahl/swift,slavapestov/swift,ken0nek/swift,tinysun212/swift-windows,roambotics/swift,allevato/swift,gmilos/swift,manavgabhawala/swift,gregomni/swift,danielmartin/swift,modocache/swift,atrick/swift,practicalswift/swift,kentya6/swift,gribozavr/swift,atrick/swift,alblue/swift,lorentey/swift,natecook1000/swift,return/swift,khizkhiz/swift,shahmishal/swift,KrishMunot/swift,cbrentharris/swift,LeoShimonaka/swift,parkera/swift,calebd/swift,swiftix/swift.old,harlanhaskins/swift,allevato/swift,KrishMunot/swift,tkremenek/swift,kentya6/swift,mightydeveloper/swift,djwbrown/swift,tjw/swift,milseman/swift,parkera/swift,xwu/swift,MukeshKumarS/Swift,jopamer/swift,amraboelela/swift,jopamer/swift,karwa/swift,djwbrown/swift,jmgc/swift,bitjammer/swift,KrishMunot/swift,KrishMunot/swift,devincoughlin/swift,russbishop/swift,natecook1000/swift,stephentyrone/swift,CodaFi/swift,airspeedswift/swift,xwu/swift,ahoppen/swift,CodaFi/swift,roambotics/swift,CodaFi/swift,ken0nek/swift,kentya6/swift,gribozavr/swift,aschwaighofer/swift,mightydeveloper/swift,OscarSwanros/swift,xedin/swift,jtbandes/swift,aschwaighofer/swift,karwa/swift,atrick/swift,amraboelela/swift,mightydeveloper/swift,JGiola/swift,CodaFi/swift,lorentey/swift,jmgc/swift,return/swift,codestergit/swift,karwa/swift,swiftix/swift,parkera/swift,lorentey/swift,modocache/swift,therealbnut/swift,jckarter/swift,djwbrown/swift,modocache/swift,swiftix/swift.old,adrfer/swift,MukeshKumarS/Swift,sdulal/swift,austinzheng/swift,MukeshKumarS/Swift,hughbe/swift,bitjammer/swift,tjw/swift,JaSpa/swift,jckarter/swift,kusl/swift,arvedviehweger/swift,gribozavr/swift,kusl/swift,tinysun212/swift-windows,deyton/swift,kusl/swift,slavapestov/swift,xedin/swift,jtbandes/swift,russbishop/swift,xedin/swift,milseman/swift,slavapestov/swift,frootloops/swift,danielmartin/swift,uasys/swift,amraboelela/swift,emilstahl/swift,danielmartin/swift,manavgabhawala/swift,felix91gr/swift,JGiola/swift,swiftix/swift.old,practicalswift/swift,xedin/swift,shajrawi/swift,karwa/swift,mightydeveloper/swift,jopamer/swift,airspeedswift/swift,sschiau/swift,natecook1000/swift,practicalswift/swift,parkera/swift,sschiau/swift,kentya6/swift,airspeedswift/swift,ahoppen/swift,bitjammer/swift,airspeedswift/swift,xedin/swift,OscarSwanros/swift,JaSpa/swift,tjw/swift,swiftix/swift,frootloops/swift,frootloops/swift,sschiau/swift,aschwaighofer/swift,nathawes/swift,aschwaighofer/swift,frootloops/swift,aschwaighofer/swift,uasys/swift,felix91gr/swift,SwiftAndroid/swift,hughbe/swift,sdulal/swift,harlanhaskins/swift,benlangmuir/swift,natecook1000/swift,shahmishal/swift,aschwaighofer/swift,rudkx/swift,brentdax/swift,Jnosh/swift,JaSpa/swift,kusl/swift,JaSpa/swift,harlanhaskins/swift,calebd/swift,modocache/swift,Ivacker/swift,ahoppen/swift,dreamsxin/swift,OscarSwanros/swift,devincoughlin/swift,return/swift,jopamer/swift,harlanhaskins/swift,uasys/swift,bitjammer/swift,arvedviehweger/swift,adrfer/swift,cbrentharris/swift,stephentyrone/swift,tinysun212/swift-windows,tjw/swift,JGiola/swift,sdulal/swift,stephentyrone/swift,gottesmm/swift,sschiau/swift,Ivacker/swift,johnno1962d/swift,stephentyrone/swift,shajrawi/swift,manavgabhawala/swift,khizkhiz/swift,airspeedswift/swift,brentdax/swift,atrick/swift,jtbandes/swift,LeoShimonaka/swift,tinysun212/swift-windows,codestergit/swift,benlangmuir/swift,gregomni/swift,hooman/swift,codestergit/swift,sdulal/swift,kusl/swift,modocache/swift,brentdax/swift,lorentey/swift,therealbnut/swift,milseman/swift,khizkhiz/swift,alblue/swift,therealbnut/swift,parkera/swift,ken0nek/swift,cbrentharris/swift,tinysun212/swift-windows,hooman/swift,KrishMunot/swift,Ivacker/swift,shahmishal/swift,kperryua/swift,brentdax/swift,tardieu/swift,rudkx/swift,ben-ng/swift,gottesmm/swift,nathawes/swift,ahoppen/swift,xwu/swift,gmilos/swift,cbrentharris/swift,slavapestov/swift,alblue/swift,ben-ng/swift,gregomni/swift,return/swift,huonw/swift,LeoShimonaka/swift,kstaring/swift,atrick/swift,codestergit/swift,nathawes/swift,russbishop/swift,therealbnut/swift,ken0nek/swift,gmilos/swift,kstaring/swift,SwiftAndroid/swift,IngmarStein/swift,calebd/swift,swiftix/swift.old,zisko/swift,ken0nek/swift,glessard/swift,amraboelela/swift,sschiau/swift,austinzheng/swift,arvedviehweger/swift,ben-ng/swift,felix91gr/swift,allevato/swift,tinysun212/swift-windows,ben-ng/swift,ben-ng/swift,natecook1000/swift,devincoughlin/swift,emilstahl/swift,apple/swift,manavgabhawala/swift,IngmarStein/swift,tjw/swift,swiftix/swift,russbishop/swift,amraboelela/swift,deyton/swift,allevato/swift,kstaring/swift,sdulal/swift,dduan/swift,gmilos/swift,swiftix/swift.old,emilstahl/swift,codestergit/swift,MukeshKumarS/Swift,IngmarStein/swift,johnno1962d/swift,SwiftAndroid/swift,danielmartin/swift,johnno1962d/swift,jtbandes/swift,jckarter/swift,swiftix/swift,swiftix/swift,felix91gr/swift,tardieu/swift,arvedviehweger/swift,brentdax/swift,adrfer/swift,hooman/swift,alblue/swift,rudkx/swift,practicalswift/swift,calebd/swift,bitjammer/swift,rudkx/swift,huonw/swift,apple/swift,apple/swift,johnno1962d/swift,allevato/swift,alblue/swift,milseman/swift,return/swift,brentdax/swift,kusl/swift,jopamer/swift,gregomni/swift,kstaring/swift,aschwaighofer/swift,arvedviehweger/swift,calebd/swift,allevato/swift,felix91gr/swift,hughbe/swift,jopamer/swift,shahmishal/swift,tardieu/swift,LeoShimonaka/swift,nathawes/swift,hughbe/swift,calebd/swift,zisko/swift,LeoShimonaka/swift,lorentey/swift,dduan/swift,deyton/swift,hooman/swift,gregomni/swift,jckarter/swift,cbrentharris/swift,felix91gr/swift,JGiola/swift,tardieu/swift,jopamer/swift,dreamsxin/swift,tjw/swift,shahmishal/swift,swiftix/swift,ahoppen/swift,zisko/swift,LeoShimonaka/swift,deyton/swift,ahoppen/swift,kstaring/swift,Jnosh/swift,MukeshKumarS/Swift,natecook1000/swift,alblue/swift,hughbe/swift,karwa/swift,zisko/swift,shajrawi/swift,devincoughlin/swift,kusl/swift,shahmishal/swift,slavapestov/swift,hughbe/swift,tinysun212/swift-windows,swiftix/swift,JaSpa/swift