* msft_github/master:
  Reorder dependencies to fix wheel build (sonic-net#117)

…onic-net#117)

Previously, psud assumed that the swsscommon library would not be installed in the unit testing environment. This is not a valid assumption, and would cause unit tests to fail if swsscommon was available in the unit test environment, because it would get imported, but there would be no Redis DB to communicate with.

This PR uses environment variables, which are set by the unit tests themselves, to determine whether to load the real or mock libraries. This solution is similar to what is done in sonic-utilities.

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Currently, in Cisco 8800 chassis, PFCWD is only enabled for front end ports, not on backplane. As we have PFC enabled for backplane ports, need to enable pfcwd there too.

#### What I did.
Enable PFCWD for backplane ports.

#### How I did it
Include backplane ports into the port list to be enabled for pfcwd

#### How to verify it

manually copied the file to device, and run pfcwd start_default.

#### Previous command output (if the output of a command-line utility has changed)

#### New command output (if the output of a command-line utility has changed)