[PATCH v3] Introduce remote_target_is_gdbserver

[Simon Marchi]

> Just a thought but... is there a specific reason we need to check for 
> gdbserver explicitly as opposed to checking for a remote debugging stub 
> feature?
> 
> It sounds more appropriate to leave remote stub-based testing as generic 
> as possible, in which case "is_gdbserver" wouldn't be needed.

Good point, but I'd rather not address this in the current patch. I don't
want to change the test itself, but just make the check available to other
tests.

Ultimately, I want to use it in this patch [1] where I really want to check
for GDBserver. I want to KFAIL a test only when using gdbserver, due to a
known bug in gdbserver.

[1] https://sourceware.org/ml/gdb-patches/2014-09/msg00148.html