UserspaceEmulator: Add support for SC_poll syscall

Author: https://github.com/boricj
Commit: 012d8d7f74
Pull-request: https://github.com/SerenityOS/serenity/pull/11229
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/IdanHo

Userland/DevTools/UserspaceEmulator/Emulator.h

@@ -196,6 +196,7 @@ private:
     FlatPtr virt$perf_register_string(FlatPtr, size_t);
     int virt$pipe(FlatPtr pipefd, int flags);
     u32 virt$pledge(u32);
+    int virt$poll(FlatPtr);
     int virt$profiling_disable(pid_t);
     int virt$profiling_enable(pid_t);
     int virt$ptsname(int fd, FlatPtr buffer, size_t buffer_size);