CMake: Use a better FindIconv.cmake
CMake: Use a better FindIconv.cmake

The current FindIconv.cmake module matches a library named "c", which happens
to match 'libc.so', which is invalid. I replaced it with a version of
FindIconv.cmake from the Orphis/boost-cmake project on github here:

https://github.com/Orphis/boost-cmake/blob/master/cmake/Modules/FindIconv.cmake

glassechidna/zxing-cpp,glassechidna/zxing-cpp