fix(api,c-api,vm) Move .cargo/config into crates

[Hywan]

Description

Rework of #1939.

We need to pass the -Wl,-E arguments to the linker when compiling wasmer, wasmer_c_api and wasmer_vm. It was done generally with a .cargo/config.toml file but it was local to our project, i.e. it was not used when Wasmer was a dependency of another project.

So we move the content of .cargo/config.toml to the respective Cargo.toml files.

Fixes #1939.
Fixes #1928.
Fixes #2107.

Review

• Add a short description of the change to the CHANGELOG.md file not necessary I guess.

[Hywan]

bors try

[bors]

try

Build failed:

• Test on linux-x64

[syrusakbary]

I had no idea this was possible.
I think we might need to add to the wasmer_vm as well (not sure how to fix it)

[Hywan]

Actually I'm not sure it's possible. I may have confused https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#platform-specific-dependencies with https://doc.rust-lang.org/cargo/reference/config.html?highlight=rustflags#configuration-format.

[Hywan]

I believe we must write build.rs scripts that emit a https://doc.rust-lang.org/cargo/reference/build-scripts.html#cargorustc-link-libkindname.

[Hywan]

Er, we can't configure RUSTFLAGS with a build.rs script, and my previous idea of using cargo-rustc-link-lib is wrong.

[Hywan]

Reference issue, rust-lang/cargo#9426.

[Hywan]

What we need exactly is rust-lang/cargo#9557: The rustc-link-arg option.

I'm going to try with rustc-cdylib-link-arg which is stable now, but is going to be renamed rustc-link-arg-cdylib in the future if I've understood everything correctly.

[Hywan]

bors try

[bors]

try

Build failed:

• Test on linux-x64

[Hywan]

bors try

[bors]

try

Build failed:

• Test on linux-x64

[Hywan]

Nah, we need to wait :-).

[syrusakbary]

Should we close this PR @Hywan ?

[Hywan]

We can keep it open and wait on Rust.