Add gypcmd extension wildcard to git ignore.

Add gypcmd extension wildcard to git ignore.

These files are generated by the msvs-ninja gyp generator.

BUG=481707
Committed: https://crrev.com/538f17a292590843ab3bbb8c202d815234e66e76
Cr-Commit-Position: refs/heads/master@{#330618}

[Will Harris, 2015-05-19 21:04:25]

wfh@chromium.org changed reviewers:
+ bradnelson@chromium.org, sbc@chromium.org

[Sam Clegg, 2015-05-19 21:05:57]

On 2015/05/19 21:04:30, Will Harris wrote:

My understanding is that these are not generated in the source tree anymore. 
Thats why I removed this entry.  Am I wrong?

[Will Harris, 2015-05-19 21:06:58]

I still get them on every checkout - see the bug for details.

[Sam Clegg, 2015-05-19 21:23:34]

On 2015/05/19 21:06:58, Will Harris wrote:
> I still get them on every checkout - see the bug for details.

lgtm, can you mention in the CL that this is because the msvs-ninja generator
still generates its files in the source tree?

[Will Harris, 2015-05-19 21:30:26]

The CQ bit was checked by wfh@chromium.org

[commit-bot: I haz the power, 2015-05-19 21:32:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1134493004/1

[commit-bot: I haz the power, 2015-05-19 21:44:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-19 21:45:52]

Patchset 1 (id:??) landed as
https://crrev.com/538f17a292590843ab3bbb8c202d815234e66e76
Cr-Commit-Position: refs/heads/master@{#330618}