Update cmake_minimum_required calls in CMakeLists.txt in Modules and in
CMakeLists.txt generated by other modules, so that they are always in
sync with current CMake version.

Use the ENV{LIB} variable directly instead of parsing the output of the
whole environment from "set".  Store the output in a .cmake script and
include it from CMakeDetermineCompilerABI instead of using file(READ).

This project is not part of the FortranCInterface module.  Make it a
sibling instead of a child directory.