Make FastISel::SelectInstruction return before target specific fast-isel code
handles Intrinsic::trap if TargetOptions::TrapFuncName is set.

This fixes a bug in which the trap function was not taken into consideration
when a program was compiled without optimization (at -O0).

<rdar://problem/16291933>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206323 91177308-0d34-0410-b5e6-96231b3b80d8