style: Replace use of Variable Length Arrays in C code

[nilason]

Current C language support for GRASS is C11 with core features, which does not include Variable Length Arrays (VLA). There are, however, a few places in the code that make use of VLAs. This leads us to either update the support directives; insert conditional code (using __STDC_NO_VLA__) ; or replace the use of such code.
Given the limited range of changes to the code, I will with this PR suggest to remove the use of VLA and make the code adhere to the RFC 7.

In addition to the code fixes, the -Wvla CFLAG is added to the Mac and Ubuntu CI builds to prevent VLA code to slip in again.

[wenzeslaus]

Oh, they were mandatory in C99, but are optional in C11. Well, we can do without them.

[nilason]

Oh, they were mandatory in C99, but are optional in C11. Well, we can do without them.

This is really not any real-life problem: some of them were introduced already in the early 2010s. But we have no actual benefit for using them either. For comparison, the use of VLAs were deliberately and actively removed from the Linux kernel, for security and efficiency reasons.

[nilason]

And, I might add, VLAs will still be optional for also for C23. It was never really a popular addition to the standard.

[echoix]

For me, it's the first time we see the auto-labeller working ;)

I was wondering about what should the imagery code be considered. Is it at the same level as raster and vector? Here, the labeller added libraries , and module for the files in top level imagery and inside lib/imagery.
Should imagery be a label itself, even if module matches a large part of our code?

[nilason]

For me, it's the first time we see the auto-labeller working ;)

I was wondering about what should the imagery code be considered. Is it at the same level as raster and vector?

Yes, along with eg. raster3d too.

Here, the labeller added libraries , and module for the files in top level imagery and inside lib/imagery. Should imagery be a label itself, even if module matches a large part of our code?

There is imagery code both in libraries as well as in modules, so this is working as intended. A proper label description might be added though and some m&m colour applied.

[echoix]

For me, it's the first time we see the auto-labeller working ;)

I was wondering about what should the imagery code be considered. Is it at the same level as raster and vector?

Yes, along with eg. raster3d too.

So it's missing labels for these. ;)

Here, the labeller added libraries , and module for the files in top level imagery and inside lib/imagery. Should imagery be a label itself, even if module matches a large part of our code?

There is imagery code both in libraries as well as in modules, so this is working as intended. A proper label description might be added though and some m&m colour applied.

Yep, the libraries and module match correctly.
Colors, I'll check it out soon.

[nilason]

Thanks @wenzeslaus !