[doxy] precompile libs script

[ferdymercury]

This Pull request:

Changes or fixes:

Precompiles C++ script to potentially speedup (slightly) documentation building

Checklist:

• tested changes locally
• updated the docs (if necessary)

[phsft-bot]

Can one of the admins verify this patch?

[ferdymercury]

@couet does this change work on your end?

[couet]

Yes it works. I am not sure if it really speed up the execution a lot. But why not doing it this may. Have you done some speed up measurement ? Note we also have more .C macros: MakeRCanvasJS.C, MakeTCanvasJS.C and makeimage.C

[couet]

It works. I merge. Potentially should it be done also for the other .C macros ?

[ferdymercury]

Yes it works. I am not sure if it really speed up the execution a lot. But why not doing it this may. Have you done some speed up measurement ? Note we also have more .C macros: MakeRCanvasJS.C, MakeTCanvasJS.C and makeimage.C

Sorry, I didn't see this message. I did not do speed-up measurements.

Concerning makeimage and the others, I tried once and saw some problems when enabling multihreading, not sure why, so I did not look into it further.

[ferdymercury]

Related: d8d71f4