* This messes less with syntax highlighting.

* See a later commit for actual improvements regarding collective
  access.

* PGI pgc++ was not detected correctly.

* Later commits will fix the underlying issues.

This reverts commit f861459a.

The underlying functionality is incompatible with MPI parallelization.

This reverts commit 039619c6.

* Unfortunately, C array parameters cannot have the restrict attribute
  thus better document the array characteristic and let the compiler
  optimize with aliasing restrictions in place.

* The second dimension of rect has indeed as many dimensions as
  appropriate for the array being written, i.e. 2 or 3 depending on
  whether a z-axis exists.

* These variables are checked via the JSON files in PIO control setups
  and should not change type unless necessary. Consistency is not a
  necessity.

* The Debian patch that prevents implicit overlinking is
partially disabled: the respective monkey patch for libtool.m4
will be implemented later. For now, test.all.nv-21.3.0 ensures
that makefiles are compatible with the patch.

This reverts commit ca953660.

At least Automake 1.16.1 does not seem to have problems with this.