[Minor] Debian: update arches and versions in build dependencies

[Minor] Debian: update arches and versions in build dependencies

* glib 2.28 is the current minimum declared in CMakeLists.txt, but even
  Jessie satisfies that requirement. Remove it.
* Use DEB_HOST_ARCH for "The Debian architecture of the host machine"
  instead of DEB_TARGET_ARCH which is relevant for cross-compiling only.
* Update luajit arches based on https://packages.debian.org/sid/luajit
  * Added arm64, mips64el, ppc64, ppc64el (stretch-backports / buster).
  * Removed kfreebsd-i386 and 32-bit powerpc (removed in Jessie).
  * Removed powerpcspe (unofficial port with outdated luajit).
  * Maintained mips (removed after buster).