rtla/timerlat: Add auto-analysis only option

rtla/timerlat: Add auto-analysis only option

Parsing and formating timerlat data might consume a reasonable
amount of CPU time on very large systems, or when timerlat
has a too short period.

Add an option to run timerlat with auto-analysis enabled while
skipping the statistics parsing. In this mode, rtla timerlat
periodically checks if the tracing is on, going to sleep waiting
for the stop tracing condition to stop tracing, or for the
tracing session to finish.

If the stop tracing condition is hit, the tool prints the auto
analysis. Otherwise, the tool prints the max observed latency and
exit. The max observed latency is captured via tracing_max_latency.

Link: https://lore.kernel.org/linux-trace-devel/4dc514d1d5dc353c537a466a9b5af44c266b6da2.1680106912.git.bristot@kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>