Make strace correctly handle SIGTRAP produced by e.g.

[Roland McGrath]

I think that has some robustness issues with the variety of kernels out
there.  Moreover, I think this is sufficiently touchy a change that we
should not be doing it before making the 4.5.19 release with existing fixes.

It's again been weeks since I said "let's release it now" and nobody has
followed up on the release work.  Let's do it already!


Thanks,
Roland