Clean up unneeded explicit pointer cast

The reference automatically coerces to a pointer. Writing an explicit
cast here is slightly misleading because that's most commonly used when
a pointer needs to be converted from one pointer type to another, e.g.
`*const c_void` to `*const sigaction` or vice versa.

library/std/src/sys/unix/process/process_unix.rs

@@ -335,7 +335,7 @@ impl Command {
             cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), ptr::null_mut()))?;
             let mut action: libc::sigaction = mem::zeroed();
             action.sa_sigaction = libc::SIG_DFL;
-            cvt(libc::sigaction(libc::SIGPIPE, &action as *const _, ptr::null_mut()))?;
+            cvt(libc::sigaction(libc::SIGPIPE, &action, ptr::null_mut()))?;
         }
 
         for callback in self.get_closures().iter_mut() {