libpacman: Simplify _pacman_sync_sysupgrade creation of to be replaced object.
libpacman: Use libflib FObject instead of local object implementation.
libpacman: Add _pacman_trans_check_package_depends.

* As a bonus check that 'reverse depends' depends are fully checked,
  might help a case of dropped provides.
libpacman: Reindent _pacman_transpkg_checkdeps.
libpacman: Increase symetry even more in _pacman_transpkg_checkdeps.

* Check required depends on the whole system when removing a package,
  not only in the about to be removed packages.
libpacman: Merge upgrade and remove path in _pacman_transpkg_checkdeps.