selftests/ftrace: fix event-no-pid on 1-core machine

When running event-no-pid test on small machines (e.g. cloud 1-core
instance), other events might not happen:

+ cat trace
+ cnt=0
+ [ 0 -eq 0 ]
+ fail No other events were recorded
[15] event tracing - restricts events based on pid notrace filtering [FAIL]

Schedule a simple sleep task to be sure that some other process events
get recorded.

Fixes: ebed9628f5c2 ("selftests/ftrace: Add test to test new set_event_notrace_pid file")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Convert required interface checks into requires list

Convert the required tracefs interface checking code with
requires: list.

Fixed merge conflicts in trigger-hist.tc and trigger-trace-marker-hist.tc
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Add test to test new set_event_notrace_pid file

A new file was added to the tracing directory that will allow a user to
place a PID into it and the task associated to that PID will not have its
events traced. If the event-fork option is enabled, then neither will the
children of that task have its events traced.

Cc: linux-kselftest@vger.kernel.org
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>