This dir include Lensfun library in case of your system do not include it.
This is typically the case of Windows, where no Lensfun package exist.

To update lensfun dir, copy all .c, .h, .cpp files, excepted:
- lensfun/include/config.h
- lensfun/include/auxfun/*
- lensfin/include/regex/*
- lensfun/libs/lensfun/mod-color-sse2.cpp
- lensfun/libs/lensfun/mod-coord-sse.cpp
- lensfun/libs/lensfun/windows/auxfun.cpp
- lensfun/libs/auxfun/*
- lensfin/libs/regex/*


Lensfun config.h file is replaced in digiKam by digikam/libs/3rdparty/lensfun/include/config-lensfun.h
File config-lenfun.cpp include a method recognized by lensfun to customize lens database file path which
can be relocated under Windows by NSIS installer.

lensfun/include/lensfun/lensfun.h file must be generated by lensfun package configured from your computer 
to set library version.

In lensfun.h, add #include "config-lensfun.h" and remove all #include "config.h" from other source files.

The XML lens Database files must be copied in digikam/data/lensfun.

