Bug#950172: gpscorrelate ftbfs with libexiv2-27

[peter green]

tags 950172 +patch
thanks

This build failure was a simple case of a missing #include "exiv2/error.hpp" , 
I fixed it in raspbian, a debdiff should appear soon at 
https://debdiffs.raspbian.org/main/g/gpscorrelate no intent to NMU in debian.