Merge changes from topic "revert-1512835-CUDUBMDOSD"

* changes:
  Revert "Canonicalize include files"
  Revert "enum-ify fixed_cid stack/include/l2cdefs::L2CAP_"
  Revert "Introduce net_test_stack_btm"
  Revert "Explicit use base::Location stack/btu/btu_hcif::"
  Revert "Add various stack/test/common/mock_"