Port parts of //third_pary/libjingle build to GN

Port parts of //third_pary/libjingle build to GN

Reimplements parts of //third_party/libjingle's build in GN.

The new build is much less flexible than the original. No
configuration variables have been ported. Some windows-specific configs
have been left out and annotated with TODOs.  Most signifcantly, the
entirety of the 'if (enable_webrtc)' block has been omitted, because the
GN build for webrtc isn't working yet.

Despite these limitations, it is an adequate replacement for the
'stub' libjingle target in most situations.

Note, this CL is a near direct copy of rlarocque's work at
   https://codereview.chromium.org/455583002/

BUG=none
TBR=sky,pavely,rlarocque

Committed: https://crrev.com/f7b1cb6926cabc20a89b2713e8c59402e6d260af
Cr-Commit-Position: refs/heads/master@{#291587}

[awong, 2014-08-22 00:59:35]

Picking this up from Richard. PTAL.

[brettw, 2014-08-22 20:13:47]

LGTM!

[awong, 2014-08-22 22:04:21]

The CQ bit was checked by ajwong@chromium.org

[commit-bot: I haz the power, 2014-08-22 22:05:03]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ajwong@chromium.org/498603002/40001

[commit-bot: I haz the power, 2014-08-22 23:31:23]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)
  win_chromium_rel_swarming on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[commit-bot: I haz the power, 2014-08-22 23:34:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-22 23:34:26]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[awong, 2014-08-22 23:46:55]

The CQ bit was checked by ajwong@chromium.org

[commit-bot: I haz the power, 2014-08-22 23:48:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ajwong@chromium.org/498603002/40001

[commit-bot: I haz the power, 2014-08-23 21:36:30]

Committed patchset #3 (40001) as 9bdda7c72c9d81d241a49645dd26fb8dabf294a4

[kjellander_chromium, 2014-08-30 06:41:25]

kjellander@chromium.org changed reviewers:
+ kjellander@chromium.org

[kjellander_chromium, 2014-08-30 06:41:25]

ajwong: I noticed a typo in this CL. Can you fix?

https://codereview.chromium.org/498603002/diff/40001/third_party/libjingle/BU...
File third_party/libjingle/BUILD.gn (right):

https://codereview.chromium.org/498603002/diff/40001/third_party/libjingle/BU...
third_party/libjingle/BUILD.gn:309: source_set("peerconnnection_server") {
This should be peerconnection_server (notice only two 'n' in connection)

[commit-bot: I haz the power, 2014-09-10 02:31:14]

Patchset 3 (id:??) landed as
https://crrev.com/f7b1cb6926cabc20a89b2713e8c59402e6d260af
Cr-Commit-Position: refs/heads/master@{#291587}