Remove XDR option and PortablePointer

[alkino]

Both of them are unused.

In the same time replace DEBUG by a direct call to fprintf.

[sonarcloud]

Quality Gate passed

Issues
21 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 SonarCloud

[azure-pipelines]

✔️ 97b349a -> Azure artifacts URL

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Project coverage is 67.40%. Comparing base (5928676) to head (97b349a).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/ivoc/checkpnt.cpp	0.00%	19 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3084   +/-   ##
=======================================
  Coverage   67.39%   67.40%           
=======================================
  Files         573      573           
  Lines      104927   104914   -13     
=======================================
- Hits        70716    70714    -2     
+ Misses      34211    34200   -11     

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[pramodk]

I don't know the origin of XDR but LGTM.

cc: @nrnhines

[nrnhines]

I think it is safe to get rid of this stuff. PortablePointer was not even used in 2007 at the start of 6.2 development and is undoubtedly a misnomer. checkpnt probably belongs in the attic. It is a part of https://nrn.readthedocs.io/en/latest/python/simctrl/programmatic.html#checkpoint
which states

There is not enough implementation at this time to make this facility useful