[Bug libgomp/85129] [openacc] Document GOMP_OPENACC_DIM

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85129

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |documentation
                 CC|                            |tschwinge at gcc dot gnu.org

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
> When deferring
> to runtime, the environment variable @var{GOMP_OPENACC_DIM} can be set.
> It has the same format as the option value, except that '-' is not
> permitted.

Thinking about it some more, this doesn't make sense to me.

If we don't specify GOMP_OPENACC_DIM, then libgomp decides on the dimensions
that haven't been decided on yet.

So if '-' means: let libgomp decide, than surely not specifying
GOMP_OPENACC_DIM is the same as specifying GOMP_OPENACC_DIM="-:-:-"

I think it's better to keep the syntax equal between fopenacc-dim and
GOMP_OPENACC_DIM.