perf, tools, script: Allow computing metrics in perf script

Add support for computing perf stat style metrics in perf script.

When using leader sampling we can get metrics for each sampling
period by computing formulas over the values of the different
group members.

This allows things like fine grained IPC tracking through sampling,
much more fine grained than with perf stat.

The metric is still averaged over the sampling period,
it is not just for the sampling point.

This patch adds a new metric output field for perf script
that uses the existing perf stat metrics infrastructure to compute
any metrics supported by perf stat.

For example to sample IPC:

$ perf record -e '{ref-cycles,cycles,instructions}:S' -a sleep 1
$ perf script -F metric,ip,sym,time,cpu,comm
...
 alsa-sink-ALC32 [000] 42815.856074:      7fd65937d6cc [unknown]
 alsa-sink-ALC32 [000] 42815.856074:      7fd65937d6cc [unknown]
 alsa-sink-ALC32 [000] 42815.856074:      7fd65937d6cc [unknown]
 alsa-sink-ALC32 [000] 42815.856074:    metric:    0.13  insn per cycle
         swapper [000] 42815.857961:  ffffffff81655df0 __schedule
         swapper [000] 42815.857961:  ffffffff81655df0 __schedule
         swapper [000] 42815.857961:  ffffffff81655df0 __schedule
         swapper [000] 42815.857961:    metric:    0.23  insn per cycle
 qemu-system-x86 [000] 42815.858130:  ffffffff8165ad0e
_raw_spin_unlock_irqrestore
 qemu-system-x86 [000] 42815.858130:  ffffffff8165ad0e
_raw_spin_unlock_irqrestore
 qemu-system-x86 [000] 42815.858130:  ffffffff8165ad0e
_raw_spin_unlock_irqrestore
 qemu-system-x86 [000] 42815.858130:    metric:    0.46  insn per cycle
           :4972 [000] 42815.858312:  ffffffffa080e5f2 vmx_vcpu_run
           :4972 [000] 42815.858312:  ffffffffa080e5f2 vmx_vcpu_run
           :4972 [000] 42815.858312:  ffffffffa080e5f2 vmx_vcpu_run
           :4972 [000] 42815.858312:    metric:    0.45  insn per cycle

TopDown:

This requires disabling SMT if you have it enabled, because
SMT would require sampling per core, which is not supported.

$ perf record -e '{ref-cycles,topdown-fetch-bubbles,topdown-recovery-bubbles,\
topdown-slots-retired,topdown-total-slots,topdown-slots-issued}:S' -a sleep 1
$ perf script --header -I -F cpu,ip,sym,event,metric,period
...
[000]     121108               ref-cycles:  ffffffff8165222e copy_user_enhanced_fast_string
[000]     190350    topdown-fetch-bubbles:  ffffffff8165222e copy_user_enhanced_fast_string
[000]       2055 topdown-recovery-bubbles:  ffffffff8165222e copy_user_enhanced_fast_string
[000]     148729    topdown-slots-retired:  ffffffff8165222e copy_user_enhanced_fast_string
[000]     144324      topdown-total-slots:  ffffffff8165222e copy_user_enhanced_fast_string
[000]     160852     topdown-slots-issued:  ffffffff8165222e copy_user_enhanced_fast_string
[000]   metric:     33.0% frontend bound
[000]   metric:      3.5% bad speculation
[000]   metric:     25.8% retiring
[000]   metric:     37.7% backend bound
[000]     112112               ref-cycles:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]     357222    topdown-fetch-bubbles:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]       3325 topdown-recovery-bubbles:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]     323553    topdown-slots-retired:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]     270507      topdown-total-slots:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]     341226     topdown-slots-issued:  ffffffff8165aec8 _raw_spin_lock_irqsave
[000]   metric:     33.0% frontend bound
[000]   metric:      2.9% bad speculation
[000]   metric:     29.9% retiring
[000]   metric:     34.2% backend bound
...

v2:
Use evsel->priv for new fields
Port to new base line, support fp output.
Handle stats in ->stats, not ->priv
Minor cleanups
Signed-off-by: Andi Kleen <ak@linux.intel.com>