[PATCH] DebugInfo: fix crash with null streamer

[Rafael Espíndola]

> I don't believe that would fix this issue - line directives still have
> to be handled by the MCStreamer due to relaxation as I understnad it,
> so the logic for creating IDs can't be moved out entirely. Well, if
> the API to the streamer just dealt with file numbers, imposed from the
> caller, is that what you're getting at? Why is that only possible with
> the fix to PR18716? (what stops us changing the MCStreamer interface
> today to only handle file numbers? I suspect it's the need to handle
> the integrated-asm case (ie: just acting as an assembler) but that
> could be addressed)

I think you are right. They are mostly independent. The nice thing
about fixing that PR is that the implementation then becomes
non-virtual since the asm streamer and the object streamer would both
work with one or multiple line tables. With that the decision of that
code moving out of the streamer becomes just a factoring decision.

Cheers,
Rafael