[Driver] -suppress-warnings and -warnings-as-errors trigger full rebuilds. (#6263)
[Driver] -suppress-warnings and -warnings-as-errors trigger full rebuilds. (#6263)

...in order to generate the correct diagnostics. It would be nice(TM)
if the suppression or warning-to-error mechanism was post-hoc, but it
isn't today, and if we ever get that we can just stop using these
flags.

rdar://problem/25560819
alblue/swift,OscarSwanros/swift,karwa/swift,felix91gr/swift,rudkx/swift,nathawes/swift,stephentyrone/swift,hooman/swift,jtbandes/swift,nathawes/swift,atrick/swift,JaSpa/swift,jckarter/swift,natecook1000/swift,ahoppen/swift,jmgc/swift,natecook1000/swift,stephentyrone/swift,austinzheng/swift,JGiola/swift,jckarter/swift,huonw/swift,benlangmuir/swift,jopamer/swift,ahoppen/swift,jckarter/swift,parkera/swift,JGiola/swift,frootloops/swift,stephentyrone/swift,harlanhaskins/swift,glessard/swift,practicalswift/swift,karwa/swift,lorentey/swift,xwu/swift,xwu/swift,stephentyrone/swift,bitjammer/swift,frootloops/swift,calebd/swift,parkera/swift,parkera/swift,zisko/swift,manavgabhawala/swift,allevato/swift,bitjammer/swift,gregomni/swift,jtbandes/swift,zisko/swift,djwbrown/swift,huonw/swift,harlanhaskins/swift,sschiau/swift,Jnosh/swift,jmgc/swift,danielmartin/swift,tkremenek/swift,sschiau/swift,uasys/swift,hughbe/swift,bitjammer/swift,brentdax/swift,alblue/swift,gribozavr/swift,aschwaighofer/swift,jtbandes/swift,amraboelela/swift,lorentey/swift,apple/swift,return/swift,brentdax/swift,alblue/swift,lorentey/swift,jtbandes/swift,devincoughlin/swift,atrick/swift,uasys/swift,karwa/swift,benlangmuir/swift,austinzheng/swift,OscarSwanros/swift,gottesmm/swift,alblue/swift,allevato/swift,gottesmm/swift,hughbe/swift,tjw/swift,JGiola/swift,djwbrown/swift,bitjammer/swift,tinysun212/swift-windows,natecook1000/swift,zisko/swift,gribozavr/swift,JaSpa/swift,bitjammer/swift,karwa/swift,calebd/swift,therealbnut/swift,allevato/swift,djwbrown/swift,jmgc/swift,deyton/swift,jtbandes/swift,uasys/swift,zisko/swift,xwu/swift,gmilos/swift,sschiau/swift,hughbe/swift,hooman/swift,danielmartin/swift,arvedviehweger/swift,codestergit/swift,ahoppen/swift,danielmartin/swift,airspeedswift/swift,bitjammer/swift,tkremenek/swift,felix91gr/swift,codestergit/swift,danielmartin/swift,manavgabhawala/swift,harlanhaskins/swift,arvedviehweger/swift,apple/swift,stephentyrone/swift,gottesmm/swift,return/swift,shahmishal/swift,OscarSwanros/swift,manavgabhawala/swift,glessard/swift,gottesmm/swift,jmgc/swift,harlanhaskins/swift,huonw/swift,calebd/swift,gribozavr/swift,stephentyrone/swift,devincoughlin/swift,shahmishal/swift,benlangmuir/swift,rudkx/swift,hughbe/swift,gribozavr/swift,uasys/swift,austinzheng/swift,aschwaighofer/swift,rudkx/swift,natecook1000/swift,hughbe/swift,nathawes/swift,austinzheng/swift,xwu/swift,shahmishal/swift,frootloops/swift,tinysun212/swift-windows,tkremenek/swift,return/swift,jckarter/swift,JGiola/swift,swiftix/swift,devincoughlin/swift,ahoppen/swift,amraboelela/swift,tjw/swift,shajrawi/swift,hooman/swift,tinysun212/swift-windows,tardieu/swift,sschiau/swift,frootloops/swift,rudkx/swift,xwu/swift,sschiau/swift,tardieu/swift,tardieu/swift,xedin/swift,xedin/swift,tkremenek/swift,austinzheng/swift,tinysun212/swift-windows,karwa/swift,hooman/swift,glessard/swift,danielmartin/swift,shahmishal/swift,gribozavr/swift,CodaFi/swift,nathawes/swift,codestergit/swift,practicalswift/swift,aschwaighofer/swift,tardieu/swift,parkera/swift,airspeedswift/swift,milseman/swift,djwbrown/swift,tardieu/swift,manavgabhawala/swift,jmgc/swift,jopamer/swift,parkera/swift,allevato/swift,benlangmuir/swift,airspeedswift/swift,airspeedswift/swift,gregomni/swift,apple/swift,huonw/swift,ahoppen/swift,felix91gr/swift,return/swift,atrick/swift,gmilos/swift,Jnosh/swift,CodaFi/swift,return/swift,JaSpa/swift,aschwaighofer/swift,uasys/swift,hughbe/swift,xedin/swift,milseman/swift,JaSpa/swift,CodaFi/swift,natecook1000/swift,apple/swift,tardieu/swift,deyton/swift,glessard/swift,CodaFi/swift,karwa/swift,brentdax/swift,glessard/swift,sschiau/swift,calebd/swift,gmilos/swift,Jnosh/swift,tjw/swift,jopamer/swift,felix91gr/swift,tjw/swift,arvedviehweger/swift,shahmishal/swift,stephentyrone/swift,jopamer/swift,natecook1000/swift,frootloops/swift,tjw/swift,sschiau/swift,amraboelela/swift,gmilos/swift,gottesmm/swift,gmilos/swift,gregomni/swift,allevato/swift,gregomni/swift,shahmishal/swift,aschwaighofer/swift,hooman/swift,shajrawi/swift,xwu/swift,lorentey/swift,frootloops/swift,jtbandes/swift,nathawes/swift,jtbandes/swift,shahmishal/swift,calebd/swift,xedin/swift,xedin/swift,danielmartin/swift,zisko/swift,hooman/swift,xedin/swift,JGiola/swift,tinysun212/swift-windows,austinzheng/swift,atrick/swift,gottesmm/swift,nathawes/swift,deyton/swift,deyton/swift,lorentey/swift,OscarSwanros/swift,milseman/swift,xedin/swift,benlangmuir/swift,amraboelela/swift,arvedviehweger/swift,gregomni/swift,ahoppen/swift,airspeedswift/swift,gribozavr/swift,shajrawi/swift,parkera/swift,jckarter/swift,tardieu/swift,karwa/swift,Jnosh/swift,milseman/swift,huonw/swift,gregomni/swift,calebd/swift,gribozavr/swift,CodaFi/swift,therealbnut/swift,brentdax/swift,tjw/swift,gmilos/swift,amraboelela/swift,manavgabhawala/swift,OscarSwanros/swift,felix91gr/swift,amraboelela/swift,atrick/swift,lorentey/swift,gribozavr/swift,harlanhaskins/swift,zisko/swift,swiftix/swift,djwbrown/swift,therealbnut/swift,huonw/swift,devincoughlin/swift,tkremenek/swift,jckarter/swift,shajrawi/swift,codestergit/swift,aschwaighofer/swift,alblue/swift,shajrawi/swift,benlangmuir/swift,hooman/swift,OscarSwanros/swift,arvedviehweger/swift,brentdax/swift,practicalswift/swift,swiftix/swift,devincoughlin/swift,deyton/swift,xwu/swift,swiftix/swift,nathawes/swift,devincoughlin/swift,therealbnut/swift,practicalswift/swift,devincoughlin/swift,return/swift,practicalswift/swift,CodaFi/swift,tinysun212/swift-windows,djwbrown/swift,gottesmm/swift,brentdax/swift,manavgabhawala/swift,arvedviehweger/swift,return/swift,therealbnut/swift,milseman/swift,devincoughlin/swift,rudkx/swift,gmilos/swift,xedin/swift,roambotics/swift,roambotics/swift,aschwaighofer/swift,rudkx/swift,Jnosh/swift,lorentey/swift,JaSpa/swift,JGiola/swift,jopamer/swift,therealbnut/swift,jmgc/swift,tkremenek/swift,milseman/swift,felix91gr/swift,OscarSwanros/swift,practicalswift/swift,calebd/swift,airspeedswift/swift,alblue/swift,parkera/swift,Jnosh/swift,hughbe/swift,huonw/swift,brentdax/swift,JaSpa/swift,sschiau/swift,danielmartin/swift,swiftix/swift,djwbrown/swift,milseman/swift,lorentey/swift,therealbnut/swift,jckarter/swift,allevato/swift,tkremenek/swift,tinysun212/swift-windows,roambotics/swift,codestergit/swift,harlanhaskins/swift,harlanhaskins/swift,Jnosh/swift,swiftix/swift,roambotics/swift,JaSpa/swift,alblue/swift,uasys/swift,shajrawi/swift,CodaFi/swift,zisko/swift,jmgc/swift,apple/swift,shahmishal/swift,codestergit/swift,bitjammer/swift,natecook1000/swift,felix91gr/swift,jopamer/swift,allevato/swift,tjw/swift,austinzheng/swift,manavgabhawala/swift,roambotics/swift,deyton/swift,apple/swift,practicalswift/swift,atrick/swift,jopamer/swift,shajrawi/swift,amraboelela/swift,airspeedswift/swift,roambotics/swift,codestergit/swift,swiftix/swift,arvedviehweger/swift,uasys/swift,glessard/swift,frootloops/swift,practicalswift/swift,karwa/swift,deyton/swift,shajrawi/swift,parkera/swift