Create a summary from perf tool output

[amirouche]

ref: https://en.wikipedia.org/wiki/Perf_%28Linux%29
ref: #12

[amirouche]

Feel free to re-open.

I will use:

scheme-live-benchmark () {
    FORMAT="command:%C\nwall-clock-time:%es\nmemory-average:%Kkb\ncpu:%P"
    /usr/bin/time -f $FORMAT $@
}

That gives the following output:

% scheme-live benchmark scheme-live chibi run local/bin/hello-schemer
Hello schemer!
command:scheme-live chibi run local/bin/hello-schemer
wall-clock-time:0.30s
memory-average:0kb
cpu:103%