Bump libc to 0.2.171 to use sigaction for AIX

Cargo.toml

@@ -34,7 +34,7 @@ members = [
 ]
 
 [dependencies]
-libc = "^0.2"
+libc = "^0.2.171"
 signal-hook-registry = { version = "^1.4", path = "signal-hook-registry" }
 
 [dev-dependencies]

signal-hook-registry/src/lib.rs

@@ -158,10 +158,7 @@ impl Slot {
     fn new(signal: libc::c_int) -> Result<Self, Error> {
         // C data structure, expected to be zeroed out.
         let mut new: libc::sigaction = unsafe { mem::zeroed() };
-        #[cfg(not(target_os = "aix"))]
-        { new.sa_sigaction = handler as usize; }
-        #[cfg(target_os = "aix")]
-        { new.sa_union.__su_sigaction = handler; }
+        new.sa_sigaction = handler as usize;
         // Android is broken and uses different int types than the rest (and different depending on
         // the pointer width). This converts the flags to the proper type no matter what it is on
         // the given platform.
@@ -239,10 +236,7 @@ impl Prev {
 
     #[cfg(not(windows))]
     unsafe fn execute(&self, sig: c_int, info: *mut siginfo_t, data: *mut c_void) {
-        #[cfg(not(target_os = "aix"))]
         let fptr = self.info.sa_sigaction;
-        #[cfg(target_os = "aix")]
-        let fptr = self.info.sa_union.__su_sigaction as usize;
         if fptr != 0 && fptr != libc::SIG_DFL && fptr != libc::SIG_IGN {
             // Android is broken and uses different int types than the rest (and different
             // depending on the pointer width). This converts the flags to the proper type no

src/low_level/signal_details.rs

@@ -111,15 +111,7 @@ fn restore_default(signal: c_int) -> Result<(), Error> {
     unsafe {
         // A C structure, supposed to be memset to 0 before use.
         let mut action: libc::sigaction = mem::zeroed();
-        #[cfg(target_os = "aix")]
-        {
-            action.sa_union.__su_sigaction = mem::transmute::<
-                usize,
-                extern "C" fn(libc::c_int, *mut libc::siginfo_t, *mut libc::c_void),
-            >(libc::SIG_DFL);
-        }
-        #[cfg(not(target_os = "aix"))]
-        { action.sa_sigaction = libc::SIG_DFL as _; }
+        action.sa_sigaction = libc::SIG_DFL as _;
         if libc::sigaction(signal, &action, ptr::null_mut()) == 0 {
             Ok(())
         } else {