Replaced __linux macro in path library

[neworderofjamie]

https://sourceforge.net/p/predef/wiki/OperatingSystems/ suggests it's deprecated but it has never been an issue apart from on a POWER9 machine. Nonethless, replacing it with the more standard __linux__ solves the problem.

[neworderofjamie]

@alexdewar - probably a little unlikely someone tries to use BoB Robotics on POWER9, but I can believe this might also not being properly set on something embedded

[codecov]

Codecov Report

Merging #363 into master will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #363      +/-   ##
==========================================
- Coverage   86.67%   86.66%   -0.01%     
==========================================
  Files          64       64              
  Lines       10138    10138              
==========================================
- Hits         8787     8786       -1     
- Misses       1351     1352       +1     

Impacted Files	Coverage Δ
src/genn/backends/cuda/optimiser.cc	75.87% <0.00%> (-0.24%)	⬇️

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[tnowotny]

Exciting stuff ;-) - obviously needs to be done.

[qhaas]

From those of us using ppc64le, thank you!

[alexdewar]

@qhaas Please tell me you are running GeNN on your POWER9? 😆

[qhaas]

your POWER9

'My' Power9, heavens no... it is the taxpayer's power9. My wife would never approve of me dropping the $$$ for my very own IBM AC922 or Raptor Talos 2, as cool as that would be ;)

But, the researcher in Issue #362 is running GeNN on that Power9 powered HPC, I was merely helping troubleshoot the compilation issue.

[alexdewar]

Ah, that does look rather big to keep at home 😉. It's pretty cool to know that you've got GeNN running on that beast though!