Modernize the codebase

[nagisa]

Reviewed best commit-by-commit.

[nagisa]

The Android failures are rust-lang/rust#103673, the freebsd issue is cross-rs/cross#1100 and I don’t really have much understanding of the wasm tool conventions to understand what that failure is about (and whether the problem is in the linker or the archiver.)

[nagisa]

NB for anybody looking at this, the last commit is very incomplete port (ran out of time!)

I am way more optimistic about having an actually working support for stack switching for windows in psm, but I believe this will also require us to add functionality to set up the stack, or at least write the documentation on how the stack ought to be allocated (and give the ability for the users to pass through the relevant information about the stack to the switch function.)

[Zoxc]

The currently remaining_stack function has quite bad code generation, so it would be nice to save the function call and the shuffling of XMM registers (on Windows), then it only needs a switch to const thread locals and some inline attributes :)

[Mrmaxmeier]

Hi,

I took a stab at some of this in interest of not having to rely on external assemblers.
(cargo-zigbuild is nice for cross compilation but zig cc recently switched to an in-house assembler which is not compatible with psm's assembly snippets.)

Here's a summary of my current status: (I haven't cleaned up my branch yet)

• The platforms with inline assembly support are done (x86, x86_64, aarch64, arm, riscv32, riscv64), but some of the new tests that rely on backtrace's stack unwinding are broken on ARM. I'd guess that these never worked properly.
• mipsel targets run into mipsel targets: compilation fails with "Undefined temporary symbol $BB0_4" rust#108835 and can probably be dropped from CI
• WASM support surfaces an issue in cc which will be fixed by Default to llvm-ar when compiling for wasm. cc-rs#657
• Linking backtrace on Android-based targets doesn't seem to be supported. I've disabled them for now, but the README states that Android targets are supported, so this should probably be fixed :/

I'm not sure why the macOS/iOS targets support a different set of directives, even for inline assembly. Rust's inline assembly guide states that the assembler is guaranteed to support .type for example, but I had to remove it for the apple targets. (Might be worth reporting upstream?)

Here's my current set of changes for reference: modernize...Mrmaxmeier:stacker:modernize
And a recent CI run: https://github.com/Mrmaxmeier/stacker/actions/runs/4379839287