build: emulate /GR- when compiling for Windows
build: emulate /GR- when compiling for Windows

The /GR- emulation is needed to support building on Windows.
std::function in Microsoft's C++ runtime requires the use of `typeid`.
We do not want to emit RTTI data.  `-frtti -fno-rtti-data` allows the
use of the `typeid` and `dynamic_cast` behaviours but will not emit the
RTTI data.  With this change, it is possible to build the Windows
runtime once again.

xwu/swift,apple/swift,atrick/swift,aschwaighofer/swift,brentdax/swift,natecook1000/swift,practicalswift/swift,allevato/swift,karwa/swift,shahmishal/swift,harlanhaskins/swift,alblue/swift,shajrawi/swift,karwa/swift,aschwaighofer/swift,CodaFi/swift,aschwaighofer/swift,sschiau/swift,practicalswift/swift,jopamer/swift,allevato/swift,tkremenek/swift,nathawes/swift,jckarter/swift,natecook1000/swift,nathawes/swift,nathawes/swift,shahmishal/swift,sschiau/swift,danielmartin/swift,JGiola/swift,shahmishal/swift,rudkx/swift,karwa/swift,sschiau/swift,roambotics/swift,airspeedswift/swift,JGiola/swift,devincoughlin/swift,natecook1000/swift,jopamer/swift,karwa/swift,gregomni/swift,harlanhaskins/swift,gregomni/swift,devincoughlin/swift,amraboelela/swift,rudkx/swift,alblue/swift,huonw/swift,alblue/swift,stephentyrone/swift,tkremenek/swift,xedin/swift,danielmartin/swift,ahoppen/swift,harlanhaskins/swift,natecook1000/swift,lorentey/swift,shahmishal/swift,amraboelela/swift,shajrawi/swift,shahmishal/swift,aschwaighofer/swift,jopamer/swift,nathawes/swift,atrick/swift,ahoppen/swift,sschiau/swift,brentdax/swift,hooman/swift,parkera/swift,tjw/swift,roambotics/swift,airspeedswift/swift,natecook1000/swift,atrick/swift,lorentey/swift,tjw/swift,jckarter/swift,lorentey/swift,austinzheng/swift,ahoppen/swift,gribozavr/swift,brentdax/swift,gribozavr/swift,amraboelela/swift,hooman/swift,airspeedswift/swift,practicalswift/swift,jopamer/swift,hooman/swift,xedin/swift,danielmartin/swift,glessard/swift,gribozavr/swift,harlanhaskins/swift,tkremenek/swift,ahoppen/swift,practicalswift/swift,stephentyrone/swift,gregomni/swift,devincoughlin/swift,allevato/swift,alblue/swift,shajrawi/swift,karwa/swift,danielmartin/swift,devincoughlin/swift,hooman/swift,xwu/swift,amraboelela/swift,apple/swift,jmgc/swift,JGiola/swift,benlangmuir/swift,karwa/swift,glessard/swift,gribozavr/swift,xedin/swift,nathawes/swift,austinzheng/swift,amraboelela/swift,glessard/swift,shajrawi/swift,sschiau/swift,karwa/swift,roambotics/swift,xwu/swift,rudkx/swift,lorentey/swift,airspeedswift/swift,huonw/swift,JGiola/swift,jmgc/swift,aschwaighofer/swift,jmgc/swift,parkera/swift,tjw/swift,lorentey/swift,devincoughlin/swift,sschiau/swift,tkremenek/swift,huonw/swift,brentdax/swift,parkera/swift,allevato/swift,roambotics/swift,harlanhaskins/swift,allevato/swift,jopamer/swift,shahmishal/swift,xwu/swift,shahmishal/swift,hooman/swift,harlanhaskins/swift,jckarter/swift,stephentyrone/swift,amraboelela/swift,apple/swift,austinzheng/swift,allevato/swift,apple/swift,xedin/swift,rudkx/swift,huonw/swift,JGiola/swift,rudkx/swift,ahoppen/swift,hooman/swift,austinzheng/swift,huonw/swift,alblue/swift,lorentey/swift,CodaFi/swift,jmgc/swift,brentdax/swift,shajrawi/swift,tjw/swift,devincoughlin/swift,danielmartin/swift,CodaFi/swift,atrick/swift,CodaFi/swift,roambotics/swift,practicalswift/swift,CodaFi/swift,huonw/swift,xedin/swift,gregomni/swift,devincoughlin/swift,parkera/swift,nathawes/swift,jopamer/swift,jopamer/swift,gribozavr/swift,jmgc/swift,jckarter/swift,gribozavr/swift,shajrawi/swift,austinzheng/swift,danielmartin/swift,tkremenek/swift,alblue/swift,brentdax/swift,brentdax/swift,practicalswift/swift,huonw/swift,sschiau/swift,CodaFi/swift,xedin/swift,tjw/swift,stephentyrone/swift,glessard/swift,parkera/swift,lorentey/swift,shajrawi/swift,aschwaighofer/swift,sschiau/swift,atrick/swift,tkremenek/swift,airspeedswift/swift,aschwaighofer/swift,apple/swift,karwa/swift,benlangmuir/swift,benlangmuir/swift,parkera/swift,natecook1000/swift,amraboelela/swift,glessard/swift,practicalswift/swift,allevato/swift,CodaFi/swift,xedin/swift,xwu/swift,airspeedswift/swift,natecook1000/swift,tjw/swift,jmgc/swift,danielmartin/swift,glessard/swift,jckarter/swift,tjw/swift,parkera/swift,austinzheng/swift,gregomni/swift,benlangmuir/swift,atrick/swift,jckarter/swift,shajrawi/swift,gribozavr/swift,xwu/swift,airspeedswift/swift,nathawes/swift,benlangmuir/swift,ahoppen/swift,devincoughlin/swift,gribozavr/swift,hooman/swift,stephentyrone/swift,shahmishal/swift,xwu/swift,stephentyrone/swift,harlanhaskins/swift,xedin/swift,JGiola/swift,jmgc/swift,austinzheng/swift,roambotics/swift,tkremenek/swift,benlangmuir/swift,parkera/swift,rudkx/swift,practicalswift/swift,apple/swift,jckarter/swift,alblue/swift,gregomni/swift,stephentyrone/swift,lorentey/swift