tracing/function-graph-tracer: provide a selftest for the function graph tracer

Making it more easy to do a basic regression test for this tracer.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --cc kernel/trace/trace.h
Simple merge

diff --cc kernel/trace/trace_functions_graph.c
Simple merge

diff --cc kernel/trace/trace_selftest.c
Simple merge