[PATCH v2] gdb, btrace: improve error messages

[Simon Marchi]

On 2022-02-01 10:01, Markus Metzger wrote:
> When trying to use 'record btrace' on a system that does not support it,
> the error message isn't as clear as it could be.  See
> https://sourceware.org/pipermail/gdb/2022-January/049870.html.
> 
> Improve the error message in a few cases.

That looks good to me, but you might want to see if the other Simon has
some feedback.

Simon