tracing/selftests: Support log output when generating KTAP output

tracing/selftests: Support log output when generating KTAP output

When -v is specified ftracetest will dump logs of test execution to the
console which if -K is also specified for KTAP output will result in
output that is not properly KTAP formatted. All that's required for KTAP
formatting is that anything we log have a '#' at the start of the line so
we can improve things by washing the output through a simple read loop.
This will help automated parsers when verbose mode is enabled.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>