Break ghidra constant folding through inline-never fns

[roblabla]

Heyo,

I just updated my project to the obfstr 4, and overall the improvements are quite nice! However, there is one small downside compared to the previous version: Obfstr 4 generates a huge block of data that xrefs every code dealing with obfuscated string in the .data block:

This is not ideal, as it gives a reverser a simple way to find all the code offsets to obfuscated strings, making the creation of an automated deobfuscation tool a bit easier.

Digging into the code, I figured that this change came from the new xref code. After reading over #44, I eventually figured that this was done to break Ghidra's constant folding which defeated much of the obfuscation.

So I tried to take a different approach here: Instead of storing the xref offsets in the .data, I figured they could be stored in a dedicated function marked inline(never). In theory, ghidra will not be able to "see through" the call, and thus break the constant folding.

Here's the result:

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This approach has the other benefits of not using the .data segment, which should make code integrity checks properly verify that the xref offsets aren't tampered with.

[CasualX]

Does the same problem not happen with the #[inline(never)] approach? There should be a ton of mov rax, OFFSET; retn funcs which you can easily enumerate as well.