Un-XFAIL validation-test/Runtime/class_stubs.m and adjust for Clang changes
Un-XFAIL validation-test/Runtime/class_stubs.m and adjust for Clang changes

The objc_loadClassref() symbol is weak linked from Clang now, so we can
un-XFAIL this test. Note that we have to pass a special flag to Clang
since objc_loadClassref() is not in the SDK's TBD files yet.

Also, change the test to use its own asserts instead of FileCheck since
there's no output unless a new libobjc is available.

shajrawi/swift,lorentey/swift,JGiola/swift,sschiau/swift,karwa/swift,jckarter/swift,CodaFi/swift,devincoughlin/swift,airspeedswift/swift,shajrawi/swift,jckarter/swift,shajrawi/swift,tkremenek/swift,shajrawi/swift,rudkx/swift,nathawes/swift,harlanhaskins/swift,tkremenek/swift,glessard/swift,devincoughlin/swift,benlangmuir/swift,hooman/swift,shajrawi/swift,shahmishal/swift,shahmishal/swift,gribozavr/swift,allevato/swift,xwu/swift,glessard/swift,jckarter/swift,gregomni/swift,stephentyrone/swift,stephentyrone/swift,atrick/swift,allevato/swift,parkera/swift,tkremenek/swift,benlangmuir/swift,atrick/swift,aschwaighofer/swift,harlanhaskins/swift,harlanhaskins/swift,ahoppen/swift,CodaFi/swift,devincoughlin/swift,gribozavr/swift,glessard/swift,roambotics/swift,lorentey/swift,jckarter/swift,gregomni/swift,gribozavr/swift,apple/swift,airspeedswift/swift,jmgc/swift,harlanhaskins/swift,devincoughlin/swift,sschiau/swift,stephentyrone/swift,sschiau/swift,karwa/swift,tkremenek/swift,aschwaighofer/swift,CodaFi/swift,jmgc/swift,sschiau/swift,xwu/swift,apple/swift,stephentyrone/swift,gribozavr/swift,xedin/swift,xedin/swift,CodaFi/swift,shajrawi/swift,roambotics/swift,gribozavr/swift,rudkx/swift,atrick/swift,airspeedswift/swift,tkremenek/swift,sschiau/swift,hooman/swift,benlangmuir/swift,stephentyrone/swift,tkremenek/swift,xedin/swift,ahoppen/swift,nathawes/swift,JGiola/swift,xedin/swift,shahmishal/swift,atrick/swift,allevato/swift,airspeedswift/swift,ahoppen/swift,aschwaighofer/swift,parkera/swift,glessard/swift,jmgc/swift,sschiau/swift,xedin/swift,roambotics/swift,CodaFi/swift,xwu/swift,jmgc/swift,aschwaighofer/swift,atrick/swift,karwa/swift,rudkx/swift,JGiola/swift,parkera/swift,parkera/swift,devincoughlin/swift,harlanhaskins/swift,gribozavr/swift,apple/swift,shahmishal/swift,JGiola/swift,airspeedswift/swift,karwa/swift,xwu/swift,shajrawi/swift,stephentyrone/swift,benlangmuir/swift,apple/swift,lorentey/swift,atrick/swift,hooman/swift,shahmishal/swift,aschwaighofer/swift,lorentey/swift,airspeedswift/swift,roambotics/swift,jckarter/swift,hooman/swift,jmgc/swift,tkremenek/swift,rudkx/swift,benlangmuir/swift,karwa/swift,devincoughlin/swift,lorentey/swift,jckarter/swift,CodaFi/swift,xwu/swift,nathawes/swift,jmgc/swift,hooman/swift,xedin/swift,stephentyrone/swift,parkera/swift,aschwaighofer/swift,shahmishal/swift,nathawes/swift,rudkx/swift,gregomni/swift,harlanhaskins/swift,ahoppen/swift,lorentey/swift,gregomni/swift,parkera/swift,JGiola/swift,allevato/swift,karwa/swift,parkera/swift,gregomni/swift,shahmishal/swift,ahoppen/swift,aschwaighofer/swift,sschiau/swift,devincoughlin/swift,lorentey/swift,sschiau/swift,harlanhaskins/swift,xedin/swift,roambotics/swift,CodaFi/swift,gribozavr/swift,benlangmuir/swift,shajrawi/swift,shahmishal/swift,lorentey/swift,parkera/swift,allevato/swift,hooman/swift,airspeedswift/swift,apple/swift,ahoppen/swift,apple/swift,xwu/swift,allevato/swift,JGiola/swift,gribozavr/swift,karwa/swift,jckarter/swift,jmgc/swift,glessard/swift,allevato/swift,devincoughlin/swift,rudkx/swift,xwu/swift,nathawes/swift,nathawes/swift,hooman/swift,roambotics/swift,karwa/swift,xedin/swift,gregomni/swift,nathawes/swift,glessard/swift