libgis: Rename ap_copy to aq for G_aprintf

[HuidaeCho]

This PR simply renames ap_copy to aq. I just like this name better from the va_copy man page ;-).

[echoix]

If there is no mentions in docs to adjust (assuming it's in the private part of the library), shouldn't be a problem.

[echoix]

But what does aq mean? Is it a convention?

[HuidaeCho]

But what does aq mean? Is it a convention?

aq next to ap just like i, j...

[echoix]

And ap was for the ap in aprintf ?

[HuidaeCho]

And ap was for the ap in aprintf ?

I think "argument pointer"?

[echoix]

Maybe aq isn't as descriptive then, since it isn't just an loop variable, but had a meaning (that variable had to be copied as we saw from the vasprintf bug that #3650 would fix)

I'm not sure enough now

[HuidaeCho]

But what does aq mean? Is it a convention?

I think it became kind of a convention because it's from the man page of va_copy:

• https://github.com/torvalds/linux/blob/master/lib/kasprintf.c
• https://github.com/rui314/8cc/blob/master/buffer.c
• https://immunant.com/blog/2019/09/variadics/
• ...

[echoix]

But what does aq mean? Is it a convention?

I think it became kind of a convention because it's from the man page of va_copy:

• https://github.com/torvalds/linux/blob/master/lib/kasprintf.c

• https://github.com/rui314/8cc/blob/master/buffer.c

• https://immunant.com/blog/2019/09/variadics/

• ...

You convinced me easily!