Fix false-positive warning 240 messages

[Daniel-Cortez]

What this PR does / why we need it:

Fixes false-positive warning 240: previously assigned value is never used messages printed for local variables in (rather rare) cases when a function first assigns a value to a static variable, then calls itself recursively and uses the assigned value in the nested call.
Example:

RecursiveFunc()
{
    static n = 0;
    if (n == 0) // assignment "n = 1" is used here in a nested call
    {
        n = 1;
        RecursiveFunc();
        n = 0; // warning 240: previously assigned value is never used (symbol "n")
    }
}

There's no way to analyze such complicated uses of static local variables accurately because the compiler works in a linear way, so as a solution I disabled tracking of unused assigned values for static variables completely.

Which issue(s) this PR fixes:

Fixes #

What kind of pull this is:

• A Bug Fix
• A New Feature
• Some repository meta (documentation, etc)
• Other

Additional Documentation:

[Daniel-Cortez]

Accidentally removed the branch for this PR (and by doing that closed the PR itself) when cleaning up the old branches, because I already used the same branch for #480 and #533. Should have used a different branch for each PR, I guess 😅
Anyway, the PR has been restored and there should be no changes from the moment it was approved.

[Y-Less]

So there's actually another bug with static locals, even when not recursive:

https://github.com/pawn-lang/YSI-Includes/blob/5.x/YSI_Visual/y_commands/y_commands_impl.inc#L463

That line gets a warning for sRet, despite the fact that it might be used here:

https://github.com/pawn-lang/YSI-Includes/blob/5.x/YSI_Visual/y_commands/y_commands_impl.inc#L485

This fix does fix that warning, but it's not really the same thing and "fix" is a bit of a stretch, so I'm reporting it anyway.