Fix typo cflags->ldflags in nss BUILD.gn on mac

Fix typo cflags->ldflags in nss BUILD.gn on mac

The gyp file has this in OTHER_LDFLAGS.

TBR=brettw@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274123

[jamesr, 2014-06-01 01:08:20]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-06-01 01:08:27]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/308003010/1

[commit-bot: I haz the power, 2014-06-01 02:38:21]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[commit-bot: I haz the power, 2014-06-01 02:38:33]

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

[commit-bot: I haz the power, 2014-06-01 02:38:33]

Try jobs failed on following builders:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[jamesr, 2014-06-01 15:15:11]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-06-01 15:15:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/308003010/1

[commit-bot: I haz the power, 2014-06-01 17:15:50]

Change committed as 274123