Compile with ENABLE_FORTRAN=ON
At present it looks like libxc already builds the Fortran libraries and modules by default, but without adding ENABLE_FORTRAN=ON the corresponding CMake targets are missing.
This commit only adds the following two files to libxc-dev.
/usr/share/cmake/Libxc/LibxcTargets-Fortran-release.cmake
/usr/share/cmake/Libxc/LibxcTargets-Fortran.cmake