perf kvm: Print kvm specific --help output

perf kvm: Print kvm specific --help output

The 'perf kvm stat record' tool is an alias of 'perf record' with
predefined kvm related options. All options that passed to 'perf kvm
stat record' are processed by the 'perf record' tool. So, 'perf kvm
stat record --help' prints help of usage for the 'perf record'
command. There are a few options useful for 'perf kvm stat record',
the rest either break kvm related output or don't change it.

Let's print safe for 'perf kvm stat record' options in addition to
general 'perf record' --help output.

With this patch, new output looks like below:

  $ perf kvm stat record -h

   usage: perf kvm stat record [<options>]

      -p, --pid <pid>       record events on existing process id
      -t, --tid <tid>       record events on existing thread id
      -r, --realtime <n>    collect data with this RT SCHED_FIFO priority
          --no-buffering    collect data without buffering
      -a, --all-cpus        system-wide collection from all CPUs
      -C, --cpu <cpu>       list of cpus to monitor
      -c, --count <n>       event period to sample
      -o, --output <file>   output file name
      -i, --no-inherit      child tasks do not inherit counters
      -m, --mmap-pages <pages>
                            number of mmap data pages
      -v, --verbose         be more verbose (show counter open errors, etc)
      -q, --quiet           don't print any message
      -s, --stat            per thread counts
      -D, --delay <n>       ms to wait before starting measurement after program start
      -u, --uid <user>      user to profile
          --per-thread      use per-thread mmaps

  $ perf kvm stat record -n sleep 1
    Error: switch `n' is not usable

   usage: perf kvm stat record [<options>]

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1413990949-13953-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>