Required for CL:1387624 which uses libtpm2 as a TPM simulator.
BUG=chromium:911799
TEST=build kokoro image, test master as well as TPM CL in it
Change-Id: I636be593a245ecd7ac10bc71319dee48e6511e97
Reviewed-on: https://chromium-review.googlesource.com/1419397
Commit-Ready: David Tolnay <dtolnay@chromium.org>
Tested-by: David Tolnay <dtolnay@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
