protobuf: remove it from portage-stable.

We backported an upstream patch and put this package to
chromiumos-overlay in CL:307861. So this one can go.

BUG=chromium:543823
TEST=cbuildbot falco-release

Change-Id: I2236ffe85aa1b58249e5be10d8da9111b0b64940
Reviewed-on: https://chromium-review.googlesource.com/309182
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
8 files changed