Add --dot option to gyp-explain

Add --dot option to gyp-explain

To allow generating a graph of linkage information that gyp-explain
outputs. Output example: http://i.imgur.com/7WWRvpA.jpg

R=thakis@chromium.org
BUG=237249
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=198806

[Nico, 2013-05-07 21:17:54]

https://codereview.chromium.org/15026004/diff/1/tools/gyp-explain.py
File tools/gyp-explain.py (right):

https://codereview.chromium.org/15026004/diff/1/tools/gyp-explain.py#newcode64
tools/gyp-explain.py:64: return prefix
os.path.commonprefix?

[scottmg, 2013-05-07 21:33:08]

On 2013/05/07 21:17:54, Nico wrote:
> https://codereview.chromium.org/15026004/diff/1/tools/gyp-explain.py
> File tools/gyp-explain.py (right):
> 
> https://codereview.chromium.org/15026004/diff/1/tools/gyp-explain.py#newcode64
> tools/gyp-explain.py:64: return prefix
> os.path.commonprefix?


That's a clever implementation:
http://svn.python.org/projects/python/trunk/Lib/genericpath.py (though it
doesn't really seem like it belongs in os.path since it's char-by-char).

Done.

[Nico, 2013-05-07 21:37:00]

lgtm

https://codereview.chromium.org/15026004/diff/7001/tools/gyp-explain.py
File tools/gyp-explain.py (right):

https://codereview.chromium.org/15026004/diff/7001/tools/gyp-explain.py#newco...
tools/gyp-explain.py:62: def GenerateDot(fro, to, paths):
"""Generates an input file for graphviz's dot program."""

[scottmg, 2013-05-07 21:51:50]

On 2013/05/07 21:37:00, Nico wrote:
> lgtm
> 
> https://codereview.chromium.org/15026004/diff/7001/tools/gyp-explain.py
> File tools/gyp-explain.py (right):
> 
>
https://codereview.chromium.org/15026004/diff/7001/tools/gyp-explain.py#newco...
> tools/gyp-explain.py:62: def GenerateDot(fro, to, paths):
> """Generates an input file for graphviz's dot program."""

Done.

[scottmg, 2013-05-07 21:58:54]

Committed patchset #3 manually as r198806 (presubmit successful).