trace: fix command help

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
run.py: add --trace option

This option enables given tracepoint from the very beginning. This is
useful if you want to enable tracing but don't want to alter the
command line.

Before:

  run.py -e " --trace=... $(cat build/release/cmdline)"

After:

 run.py --trace=...

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
run.py: add --trace-backtrace option

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
trace: make 'prof' show all trace samples by default

Often profile has only one tracepoint, let's save users some typing by
showing all by default.

Before:

  trace prof -t sched_wait

After:

  trace prof

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
trace: auto-paginate output using less

Instead of:

  trace list | less

just do:

  trace list

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
trace: use "tracefile" by default

It is cumbersome to have to type "file" on every trace command. Let's
use "tracefile" by default.

Before:

 trace extract file
 trace summary file
 trace prof file

After:

 trace extract
 trace summary
 trace prof

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>