[fpc-pascal] Smart-linking versus Whole Program Optimization

[LacaK]

>> It will be nice have this in documentation. For example in
>> https://www.freepascal.org/docs-html/prog/progse30.html#x195-2000007.3
>>
>> At least explain:
>> - relation of -CX and -XX
> Indeed.
>
>> - what is to be removed: non-referenced non-virtual methods, global
>> variables, and regular procedures/functions
> Disagreed. Those are implementation details, may vary from target to
> target, may depend on the assembler/linker rather than on FPC, etc. What
> I wrote is just the high level idea. When you have e.g. published
> properties and their RTTI, you can easily start having a lot of hidden
> references.
I do not insist that it must be written in this way, but something 
should be there explained.

Goal is that: reader should understand what can expect from smart-linking.

-Laco.