D13102: Don't include a 64 when building 64bit architectures on flatpak

[Aleix Pol Gonzalez]

apol added a subscriber: eszlari.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D13102

To: apol, #frameworks
Cc: eszlari, kde-frameworks-devel, kde-buildsystem, michaelh, ngraham, bruns