REVIEWED: Remove some `const` from text buffer return values
Lately got some compilation `errors` related, it seems GCC 14 interprets some `const`-missmatch as errors instead of warnings (as previous versions).
But in any case, I don't see why an user won't be able to operate directly over of those returned buffers; `const` adds a restriction (for security reasons?) that in my opinion is useless.
From an expert on compilers (w64devkit creator), here there are some notes I agree with:
```
No const. It serves no practical role in optimization, and I cannot recall an instance where it caught, or would have caught, a mistake. I held out for awhile as prototype documentation, but on reflection I found that good parameter names were sufficient. Dropping const has made me noticeably more productive by reducing cognitive load and eliminating visual clutter. I now believe its inclusion in C was a costly mistake.
(One small exception: I still like it as a hint to place static tables in read-only memory closer to the code. I’ll cast away the const if needed. This is only of minor importance.)
```
Ref: https://nullprogram.com/blog/2023/10/08/