GN: Fix error in is_component_build in boringssl

GN: Fix error in is_component_build in boringssl

It's trying to append to a list that doesn't exist yet.

R=brettw@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285787

[brettw, 2014-07-25 22:44:07]

lgtm

[commit-bot: I haz the power, 2014-07-25 22:45:35]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/424453002/1

[commit-bot: I haz the power, 2014-07-26 00:03:29]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)
  mac_gpu_retina_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_retina_tr...)
  mac_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_triggered...)

[commit-bot: I haz the power, 2014-07-26 19:38:48]

Change committed as 285787