trunks: Move BackgroundCommandTransceiver into libtrunks

This CL moves the BackgroundCommandTransceiver class into libtrunks
so that clients of trunks can make use of it. Also fixes a small bug
in SendCommand.

BUG=None
TEST=FEATURES=test emerge-link trunks

Change-Id: Ib8167e8f01e09a8a78843751f87881203fe8a062
3 files changed
tree: dad83e8d2f11af711930d11bd2687764ce410c42
  1. attestation/
  2. tpm_manager/
  3. trunks/
  4. MODULE_LICENSE_APACHE2
  5. NOTICE