[libdispatch] Linux build fixes
[libdispatch] Linux build fixes

    * Dispatch's shims header file was not adequately protected against
    building on Linux (which does not have the blocks runtime).

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