kill: Replace LibC kill call with LibCore equivalent

Author: https://github.com/tcl3
Commit: c1b3b4d6d8
Pull-request: https://github.com/SerenityOS/serenity/pull/19156
Reviewed-by: https://github.com/gmta ✅

Userland/Utilities/kill.cpp

@@ -70,8 +70,6 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
     pid_t pid = pid_opt.value();
 
-    int rc = kill(pid, signum);
+    TRY(Core::System::kill(pid, signum));
-    if (rc < 0)
-        perror("kill");
     return 0;
 }