* This will enable functions in pio_interface later to be written
  without regard for header specifics.

* This allows to have the offset entry available for all types.

* This ensures a consistent traversal on all I/O tasks.

* This ensures synchronization.

* The added pkg.m4 accounts for pkg.m4 sometimes not being available or
  having another version.

* If these are set they already override the corresponding variable.
* Also reduce number of spurious linefeeds in configure.