Reland protobuf tombstones.

This reverts the following commits:
    e156ede145a7fc671c705d045d89b49922a758b5.
    eda96eddcbdda9632166232b2363c7b84da0994d.
    5ec54d1e843729cd1e38a2f791f001226a653e95.
    1e45d3f2239333217d3252f78151f4294fda4e80.
    a50f61f8fa903117a6df82d164628de310f16ae9.

Test: treehugger
Test: atest -c CtsSeccompHostTestCases:android.seccomp.cts.SeccompHostJUnit4DeviceTest#testAppZygoteSyscalls
Change-Id: Ic2b1f489ac9f1fec7d7a33c845c29891f4306bbd
25 files changed