Update coverage tests for VxWorks at minimum to include reporting of all code that could be included in build

[skliper]

Is your feature request related to a problem? Please describe.
Currently os-impl-bsd-socket.c can be included (and is by default) in the VxWorks build:

osal/src/os/vxworks/CMakeLists.txt

Line 67 in 09a2c5e

../portable/os-impl-bsd-sockets.c # Use BSD socket layer implementation

but it's not included in coverage testing or reported as part of status

osal/src/unit-test-coverage/vxworks/CMakeLists.txt

Line 31 in 09a2c5e

#bsd-sockets

So although code coverage reports 100%, we are NOT covering the possible FSW 100%... so it's a bit misleading.

Describe the solution you'd like
All possible code should be reported for coverage. Short term is just to add tests (track by hand) but eventually may benefit from a quick check that all the files included in the build are included in coverage analysis.

Describe alternatives you've considered
None

Additional context
Illuminated by investigation into #793, unreachable code wasn't being reported even though it was in the core build.

Requester Info
Jacob Hageman - NASA/GSFC