[osg] windows-static builds of dependent ports fail (e.g. osg-qt)

[Neumann-A]

Reason: CMake dependent ports will always assume shared build on windows.
From include/osg/Export

#if defined(_MSC_VER) || defined(__CYGWIN__) || defined(__MINGW32__) || defined( __BCPLUSPLUS__)  || defined( __MWERKS__)
    #  if defined( OSG_LIBRARY_STATIC )
    #    define OSG_EXPORT
    #  elif defined( OSG_LIBRARY )
    #    define OSG_EXPORT   __declspec(dllexport)
    #  else
    #    define OSG_EXPORT   __declspec(dllimport)
    #  endif
#else
    #  define OSG_EXPORT
#endif

Since CMake findModule for OSG will not automatically pass OSG_LIBRARY_STATIC linkage against OSG will fail in static builds on windows. As such if defined( OSG_LIBRARY_STATIC ) should be changed to if TRUE for static windows builds

[JackBoosY]

I will fix them after #10082 merged.

[JackBoosY]

@Neumann-A I see that many header files contain similar content. Should we define OSG_LIBRARY_STATIC in one file to solve this issue? And which header file do we usually include osg first?

[LilyWangLL]

@Neumann-A I see that many header files contain similar content. Should we define OSG_LIBRARY_STATIC in one file to solve this issue? And which header file do we usually include osg first?

Ping @Neumann-A for response.

[Neumann-A]

Just define it before the api export defs