Log Message:
Update to 0.2.6.

pkgsrc notes:
* I know 0.2.7 is out; it has issues on ubuntu so I'm doing this first.
* patch-ac should perhaps be dropped.

Upstream NEWS content (from web page):

* more than 40 new database entries of lenses and compact cameras
* new CMake based build system for better cross platform compatibility
  and compilation fixes for MSVC
* better integration into hugin for loading and storing lens
  parameters via the lensfun library
* several bug fixes and stability improvements