make install fails to install idx2Config.cmake

[philip-davis]

It looks like either idx2Config.cmake is missing from the repo, or the cmake configuration to generate it is missing. I get:

CMake Error at Source/cmake_install.cmake:73 (file):
  file INSTALL cannot find "/home/pdavis/idx2/Source/idx2Config.cmake": No
  such file or directory.
Call Stack (most recent call first):
  cmake_install.cmake:47 (include)

and indeed that file does not exist.