[CImgPlugin] FIX CMakeLists install fail since pluginization

[marques-bruno]

Hello,

Since we talked about it during the SofaDev meeting,
Here's our QuickNDirty answer to the make install fail for CImgPlugin.
Of course as-is it is not acceptable or mergeable but it's here

---

This PR:

• builds with SUCCESS for all platforms on the CI.
• does not generate new warnings.
• does not generate new unit test failures.
• does not generate new scene test failures.
• does not break API compatibility.
• is more than 1 week old (or has fast-merge label).

Reviewers will merge only if all these checks are true.

[guparan]

Even in the eventuality that more changes are needed to actually clean the installation of SOFA, these changes still are needed.
So LGTM 👍

[damienmarchal]

Hi all,

Thank bruno for the PR.

@guparan I'm not sure we should merge this now.
Do we really want to remove the config.h from the CMakeLists ?
Wouldn't it be better to use static config.h instead of config.h.in ?

Having a .in means that the file is a template that is transformed by CMakeLists. This is not the case here so the .in file is misleading and useless. In case we prefer an autogenerated config.h.in from a template it would be much better to have a single one instead of one per plugin/module.
Eg of what could be the content of such a config.h.in:

/// This file is autogenerated by CMakeLists.txt please do not edit. 
#ifndef @PROJECT_CNAME@_CONFIG_H
#define @PROJECT_CNAME@_CONFIG_H

#include <SofaBase/config.h>

#ifdef SOFA_BUILD_@PROJECT_CNAME@
#  define SOFA_TARGET @PROJECT_NAME@
#  define SOFA_@PROJECT_CNAME@_API SOFA_EXPORT_DYNAMIC_LIBRARY
#else
#  define SOFA_@PROJECT_CNAME@_API SOFA_IMPORT_DYNAMIC_LIBRARY
#endif

#endif /// @PROJECT_CNAME@_CONFIG_H

[guparan]

[ci-build][with-scene-tests]