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
which is managed and configured by CMake.

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

In all lensfun source code, replace all #include "config.h" by #include "config-lensfun.h".

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

