system_api: adding constant for OpenVPN.TLSVersionMin support

Adding kOpenVPNTLSVersionMin constant

BUG=chromium:707517
TEST=Unit tests still work
Change-Id: I3e23c75e4e482d59eed5909f0af7729a22b5d862
Reviewed-on: https://chromium-review.googlesource.com/753427
Commit-Ready: Matthew Wang <matthewmwang@chromium.org>
Tested-by: Matthew Wang <matthewmwang@chromium.org>
Reviewed-by: Kevin Cernekee <cernekee@chromium.org>
1 file changed