uucore: disable default signal-handlers added by Rust

Fixes uutils#6759

Test procedure (verifies that a single SIGSEGV stops a program):
```
ecordonnier@lj8k2dq3:~/dev/coreutils$ ./target/release/coreutils sleep 100 &
[1] 4175464
ecordonnier@lj8k2dq3:~/dev/coreutils$ kill -11 $(pidof coreutils)
ecordonnier@lj8k2dq3:~/dev/coreutils$
[1]+  Segmentation fault      (core dumped) ./target/release/coreutils sleep 100
```

src/uucore/src/lib/features/signals.rs

@@ -14,7 +14,7 @@
 use nix::errno::Errno;
 #[cfg(unix)]
 use nix::sys::signal::{
-    signal, SigHandler::SigDfl, SigHandler::SigIgn, Signal::SIGINT, Signal::SIGPIPE,
+    sigaction, signal, SigHandler::SigDfl, SigHandler::SigIgn, Signal::SIGINT, Signal::SIGPIPE, Signal::SIGBUS, Signal::SIGSEGV, SigSet, SaFlags, SigAction
 };
 
 /// The default signal value.
@@ -387,6 +387,25 @@ pub fn ignore_interrupts() -> Result<(), Errno> {
     unsafe { signal(SIGINT, SigIgn) }.map(|_| ())
 }
 
+// Disables the custom signal handlers installed by Rust for stack-overflow handling. With those custom signal handlers processes ignore the first SIGBUS and SIGSEGV signal they receive.
+// See https://github.com/rust-lang/rust/blob/8ac1525e091d3db28e67adcbbd6db1e1deaa37fb/src/libstd/sys/unix/stack_overflow.rs#L71-L92 for details.
+#[cfg(unix)]
+pub fn disable_rust_signal_handlers() -> Result<(), Errno> {
+    unsafe {
+        sigaction(
+            SIGSEGV,
+            &SigAction::new(SigDfl, SaFlags::empty(), SigSet::all()),
+        )
+    }?;
+    unsafe {
+        sigaction(
+            SIGBUS,
+            &SigAction::new(SigDfl, SaFlags::empty(), SigSet::all()),
+        )
+    }?;
+    Ok(())
+}
+
 #[test]
 fn signal_by_value() {
     assert_eq!(signal_by_name_or_value("0"), Some(0));

src/uucore_procs/src/lib.rs

@@ -24,6 +24,9 @@ pub fn main(_args: TokenStream, stream: TokenStream) -> TokenStream {
 
     let new = quote!(
         pub fn uumain(args: impl uucore::Args) -> i32 {
+            #[cfg(unix)]
+            uucore::signals::disable_rust_signal_handlers().expect("Disabling rust signal handlers failed");
+
             #stream
             let result = uumain(args);
             match result {