Re-enable building of static libraries.
Re-enable building of static libraries.

Add a proper build option SWIFT_BUILD_STATIC to support building
static libraries. Default this option to the old build setting,
ENABLE_SWIFT_STATIC_RUNTIME, which has an unfortunate name and was
never a proper build option. <rdar://problem/17648470>

This commit is only sufficient for building static libraries for
non-SDK builds. SDK build support to follow.

Note that Xcode projects built with SWIFT_BUILD_STATIC don't quite
work: Xcode refuses to build the static library if it doesn't contain
any files that Xcode itself builds, e.g., if there are no
.m/.c/.mm/.cpp files in the target.

Swift SVN r19940

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