Consider replacing preprocessor wrapping with linker options

[MasonRemaley]

Right now, we wrap symbols like dlopen via the preprocessor. We also do this to namespace symbols that would otherwise conflict.

This works, but if possible, it'd be nicer to do this with a linker arg like --wrap, or via a linker script, since this is a bit more direct (no chance of renaming anything unintended) and would likely allow us to avoid exposing implementation details like glibc's open_2.

I've opted not to do this for now since I don't want to introduce a dependency on a specific linker. Building with Zig's non-llvm x64 backend in debug mode is super useful, it's not worth breaking that workflow over this. IIRC there are plans for Zig to get its own linker script setup that would allow setting up linker scripts in a cross-linker way, once that happens this should be revisited.

(h/t deivid)

[MasonRemaley]

See also comment from @andrewrk, copied here in case the lobsters thread disappears:

The C preprocessor is a safer dependency than a linker feature. Linker functionality is not standardized and different features have different degrees of how prevalent they are among the linker implementations. Linker arguments also bypass the compiler frontend and can therefore cause confusing problems that the compiler can't help troubleshoot because it doesn't understand semantically what your linker arguments are doing. In general it's better to avoid passing arguments to the linker.

With Zig specifically, all linker arguments are implemented in the frontend, understood by the compiler, and filtered down to the linker layer. This means however that arbitrary linker arguments are not supported; only those which have been properly integrated with the compiler. You can't just bypass the compiler and give args to the linker.

For this particular -wrap feature, however, it looks like zig does have support for it. Looks like it hasn't been integrated with the -fno-lld linkers yet though.