[RFA] Fix regcache leak, and avoid possible regcache access after detach.

[Philippe Waroquiers]

On Tue, 2019-02-19 at 16:44 -0700, Kevin Buettner wrote:
> Okay with those changes, assuming that all goes well with the
> native-gdbserver testing.
Thanks for the review.

I have just pushed the patch, after doing the suggested fixes,
successfully tested with native gdbserver, and waited for the
branching just to be sure.

Philippe