ArrayOpts: handle local variable arrays, not just inout args.
ArrayOpts: handle local variable arrays, not just inout args.

This improves RC4 at -Ofast by ~2.7x.

It also makes microbenchmarks more robust. Without this, we were
seeing dramatic performance artifacts due to inlining differences.

For example, if you remove the @inline attribute from Quicksort, this
will give us a 10x speedup.

Here are the >5% differences:

| benchmark     | base -O3 |  opt -O3 |  delta | speedup |
| RC4           |   746.00 |   686.00 |  60.00 |    8.7% |
| Histogram     |  1147.00 |  1086.00 |  61.00 |    5.6% |
| StringWalk    |  1334.00 |  1265.00 |  69.00 |    5.5% |
| SmallPT       |  1124.00 |  1069.00 |  55.00 |    5.1% |

(I think the non-RC4 results might be bogus)

| benchmark     |base-Ofast|opt -Ofast|   delta | speedup |
| RC4           |  1094.00 |   405.00 |  689.00 |  170.1% |
| EditDistance  |  1727.00 |  1396.00 |  331.00 |   23.7% |
| StringWalk    |  1043.00 |   937.00 |  106.00 |   11.3% |
| Dictionary    |   930.00 |  1009.00 |   79.00 |   -7.8% |
| Phonebook     |  2270.00 |  2131.00 |  139.00 |    6.5% |
| StringBuilder |  1842.00 |  1723.00 |  119.00 |    6.9% |

RC4 is definitely real. It's always between 2.5-3x faster.

The others are very flaky.

Swift SVN r20445

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