Improve has_realtime_kernel method

[saikishor]

These changes allow the detection of realtime kernel even from the uname output. It should be more robust.

Fixes: #257

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 69.13%. Comparing base (db891ef) to head (233e1fd).

Files with missing lines	Patch %	Lines
src/realtime_helpers.cpp	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #260      +/-   ##
==========================================
- Coverage   70.12%   69.13%   -0.99%     
==========================================
  Files           8        8              
  Lines         492      499       +7     
  Branches       84       86       +2     
==========================================
  Hits          345      345              
- Misses         92       99       +7     
  Partials       55       55              

Flag	Coverage Δ
unittests	69.13% <0.00%> (-0.99%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/realtime_helpers.cpp	37.14% <0.00%> (-2.66%)	⬇️

[alexswerner]

I think the approach is OK, but one thought:

• using #if !defined(_WIN32) on a feature which is Linux specific might be the wrong test

Hopefully the kernel uname output will always include this.

[saikishor]

@alexswerner yes! I had to do that to make the Windows CI work. If not, it doesn't compile at all. Maybe, I can fix it differently

[saikishor]

@alexswerner done!