Rollup merge of #126146 - devnexen:signal_fbsd, r=ChrisDenton

std::unix::process adding few specific freebsd signals to be able to id.

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

@@ -1053,6 +1053,10 @@ fn signal_string(signal: i32) -> &'static str {
         libc::SIGINFO => " (SIGINFO)",
         #[cfg(target_os = "hurd")]
         libc::SIGLOST => " (SIGLOST)",
+        #[cfg(target_os = "freebsd")]
+        libc::SIGTHR => " (SIGTHR)",
+        #[cfg(target_os = "freebsd")]
+        libc::SIGLIBRT => " (SIGLIBRT)",
         _ => "",
     }
 }