commit c29a7a7580c525332460df5043fcb1f4a524cad2
author Todd Wang <toddw@google.com> Mon Oct 19 22:41:33 2015 -0700
committer Todd Wang <toddw@google.com> Mon Oct 19 22:41:33 2015 -0700
tree 9221fad951c75c7f8cb0ce50ea88caf0932e7027
parent e8ec36e6e91bab717edc73211f9e289d2e2d4764

lib: Added v.io/x/lib/timing package.

Adds the timing package, which provides utilities for collecting
trees of timing information and dumping it with a nice format.
An example of the output format:

00:00:01.000 root       98.000s       00:01:39.000
00:00:01.000    *           9.000s    00:00:10.000
00:00:10.000    foo        45.000s    00:00:55.000
00:00:10.000       *           5.000s 00:00:15.000
00:00:15.000       foo1       22.000s 00:00:37.000
00:00:37.000       foo2       18.000s 00:00:55.000
00:00:55.000    bar        25.000s    00:01:20.000
00:01:20.000    baz        19.000s    00:01:39.000

Also add this support to the cmdline package via the -time flag,
and add some preliminary timings for "jiri update".

MultiPart: 3/4

Change-Id: Ic22476e7b75ad31756eec8b6554991dd885b7632