Add testTrap SILCombine (DCE) test case
Add testTrap SILCombine (DCE) test case

Before isReadOnlyConstantEvaluableCall is fixed to recognize that
[_semantics "programtermination_point"] is not a read-only function,
this test will fail as soon as SILCombine is fixed to recognize all
dead code (e.g. by using the InstructionDeleter API).

benlangmuir/swift,glessard/swift,JGiola/swift,ahoppen/swift,JGiola/swift,apple/swift,apple/swift,glessard/swift,ahoppen/swift,apple/swift,benlangmuir/swift,gregomni/swift,glessard/swift,atrick/swift,atrick/swift,apple/swift,rudkx/swift,apple/swift,roambotics/swift,rudkx/swift,gregomni/swift,JGiola/swift,glessard/swift,roambotics/swift,roambotics/swift,apple/swift,benlangmuir/swift,ahoppen/swift,JGiola/swift,glessard/swift,rudkx/swift,ahoppen/swift,gregomni/swift,gregomni/swift,ahoppen/swift,roambotics/swift,rudkx/swift,rudkx/swift,glessard/swift,benlangmuir/swift,benlangmuir/swift,JGiola/swift,roambotics/swift,atrick/swift,ahoppen/swift,atrick/swift,gregomni/swift,gregomni/swift,atrick/swift,JGiola/swift,benlangmuir/swift,rudkx/swift,roambotics/swift,atrick/swift