vpn-manager: Update gyp files to use libchromeos from src/platform2

libchromeos was moved from src/platform to src/platform2. This CL updates
the gyp files to use the new location.

TEST=FEATURES=test emerge-amd64-generic platform2
TEST=trybot run on daisy, link, mario and duck


Change-Id: I338e280e9e75c22c84617fa89d3c255de5150223
Reviewed-on: https://chromium-review.googlesource.com/202328
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Bertrand Simonnet <bsimonnet@chromium.org>
1 file changed