LLVM doesn't support non-call exception. This test was passing
    more or less by luck: if the faulting instruction is between two
    calls with the same landing pad (in instruction layout order,
    not the program's logic order), it generates a merged PC range
    that covers the faulting instruction. If the instruction layout
    order changes, or it uses two different (but may be degenerate)
    landing pads, this doesn't work.
    
    Reviewed-on: https://go-review.googlesource.com/c/140517

From-SVN: r264985