Revert "[CMake] Clear the Clang module cache before building the ObjectiveC overlay."
Revert "[CMake] Clear the Clang module cache before building the ObjectiveC overlay."

This broke systems where it isn't appropriate to clear the module cache.
The build script already does this when you do a full build; for other
cases, we should just deal with it. (You can still specify a custom
MODULE_CACHE_PATH to make it easier to delete, rather than relying on the
system one.)

This reverts commit r14364.

<rdar://problem/16232176>

Swift SVN r14872

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