[CMake] Protobuf on iOS

[Robert Bielik]

Thanks Craig,

For your thorough answer!

> set(CMAKE_MACOSX_BUNDLE YES)

I did set this so that the protoc app would get through compilation, but since the protobuf cmake/install.cmake file contains the following:

install(TARGETS protoc ... RUNTIME DESTINATION ...) it chokes since BUNDLE DESTINATION is not defined, so I had to add that.

The targets are all static libs so code signing is not a problem at this point.

All the best,
/Robert