[PATCH] Fix gdb.trace/mi-traceframe-changed.exp to check for target trace support

[Yao Qi]

On 01/10/2014 05:21 AM, Sergio Durigan Junior wrote:
> gdb.trace/mi-traceframe-changed.exp was running without actually
> checking if the target supported tracing or not.  So I wrote this patch
> to fix the issue.

The patch looks a right fix.  Any tracepoint related tests should check
whether target supports tracing or not at first.

I did it through an oversight when I wrote this case.

-- 
Yao (齐尧)