Revert of mac: Weakly link against the CoreBluetooth framework.

Revert of mac: Weakly link against the CoreBluetooth framework. (patchset #2 id:80001 of https://codereview.chromium.org/1101513003/)

Reason for revert:
Looks like this broke the Mac GN build:

http://build.chromium.org/p/chromium.mac/builders/Mac%20GN%20(dbg)/builds/8764

device/BUILD.gn needs to include //build/config/mac/mac_sdk.gni ,  I think.

Original issue's description:
> mac: Weakly link against the CoreBluetooth framework.
> 
> In the OSX 10.10 SDK, CoreBluetooth became a top level framework. Previously,
> it was nested in IOBluetooth. In order for Chrome to run on OSes older than OSX
> 10.10, the top level CoreBluetooth framework must be weakly linked.
> 
> BUG=463170
> 
> Committed: https://crrev.com/9fde3e00865650009c7e85fcb7157719372b97a8
> Cr-Commit-Position: refs/heads/master@{#326705}

TBR=rsesek@chromium.org,keybuk@chromium.org,erikchen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=463170

[Dirk Pranke, 2015-04-24 01:06:44]

Created Revert of mac: Weakly link against the CoreBluetooth framework.

[commit-bot: I haz the power, 2015-04-24 01:07:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1098123004/1

[commit-bot: I haz the power, 2015-04-24 01:07:57]

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

[commit-bot: I haz the power, 2015-04-24 01:07:58]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-04-24 01:08:30]

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

[Dirk Pranke, 2015-04-24 01:11:02]

On 2015/04/24 01:07:58, I haz the power (commit-bot) wrote:
> Failed to apply the patch.

Already reverted, apparently. Closing.