Both c.rs and stack_overflow.rs had bindings of libc's signal-handling
routines. It looks like the split dated from #16388, when (what is now)
c.rs was in libnative but not libgreen. Nobody is currently using the
c.rs bindings, but they're a bit more accurate in some places.
Move everything to c.rs (since I'll need signal handling in process.rs,
and we should avoid duplication), clean up the bindings, and manually
double-check everything against the relevant system headers (fixing a
few things in the process).
Inspecting the current thread's info may not always work due to the TLS value
having been destroyed (or is actively being destroyed). The code for printing
a panic message assumed, however, that it could acquire the thread's name
through this method.
Instead this commit propagates the `Option` outwards to allow the
`std::panicking` module to handle the case where the current thread isn't
present.
While it solves the immediate issue of #24313, there is still another underlying
issue of panicking destructors in thread locals will abort the process.
Closes#24313
This commit merges the `rustrt` crate into `std`, undoing part of the
facade. This merger continues the paring down of the runtime system.
Code relying on the public API of `rustrt` will break; some of this API
is now available through `std::rt`, but is likely to change and/or be
removed very soon.
[breaking-change]
