[PATCHSET] Update Rust frontend 19/03/2024 2/4

[arthur.cohen@embecosm.com]

Hi everyone,

This is the second of the patchsets we plan on upstreaming in the coming
days. This one notably contains the commit which fixes PR119353, which
had not yet been upstreamed but was present in our development repo for
a while. We will continue working on improving our support for all
distributions when it comes to our Rust code, and plan on finishing
downgrading our minimum Rust version to 1.49 in time for GCC 15.1. This
will also enable gccrs to compile its own Rust component once it becomes
more mature.

This patchset contains multiple additions to the borrow-checker, handling
for a lot of required attributes used in Rust's `core` crate, more
additions to our handling of inline assembly, and multiple type-system
fixes.

Thanks again for all the testing and bug reports. We'll keep on
investigating the failures found with the last patchset.

Best regards,

Arthur