Statically link libprotobuf_lite on Linux

Chrome has a direct dependency on a custom libprotobuf_lite in
third_party, but Xenial and Yakkety add a dependency on the system
libprotobuf-lite via Mir (which gets loaded from Gtk).

Our third_party protobuf is not compatible with the upstream protobuf.
Combine this with the fact that Xenial uses version 2 while Yakkety
uses version 3, and it's basically impossible to make our third_party
protobuf cooperate with the system one.  The solution is to always
statically link protobuf on Linux.

BUG=79722,700120
R=pkasting@chromium.org
TBR=bengr@chromium.org
CC=dpranke@chromium.org,rsimha@chromium.org

Review-Url: https://codereview.chromium.org/2746493002
Cr-Commit-Position: refs/heads/master@{#455936}
2 files changed