Use PyBool_FromLong instead of macros

[JCGoran]

• use PyBool_FromLong (part of stable ABI/limited API) instead of macros
• simplify some logic to use less branching

As an impl detail, the function is defined in cpython as:

PyObject *PyBool_FromLong(long ok)
{
    return ok ? Py_True : Py_False;
}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[azure-pipelines]

✔️ 97d2bb7 -> Azure artifacts URL

[codecov]

Codecov Report

Attention: Patch coverage is 26.66667% with 11 lines in your changes missing coverage. Please review.

Project coverage is 67.07%. Comparing base (9500741) to head (97d2bb7).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
src/nrnpython/nrnpy_nrn.cpp	22.22%	7 Missing ⚠️
src/nrnpython/nrnpy_hoc.cpp	33.33%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3305   +/-   ##
=======================================
  Coverage   67.07%   67.07%           
=======================================
  Files         571      571           
  Lines      111055   111038   -17     
=======================================
- Hits        74488    74484    -4     
+ Misses      36567    36554   -13     

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