[signal] Add default value for params (#14448)

Author: donBarbos

stdlib/signal.pyi

@@ -181,7 +181,7 @@ else:
 def strsignal(signalnum: _SIGNUM, /) -> str | None: ...
 def valid_signals() -> set[Signals]: ...
 def raise_signal(signalnum: _SIGNUM, /) -> None: ...
-def set_wakeup_fd(fd: int, /, *, warn_on_full_buffer: bool = ...) -> int: ...
+def set_wakeup_fd(fd: int, /, *, warn_on_full_buffer: bool = True) -> int: ...
 
 if sys.platform == "linux":
-    def pidfd_send_signal(pidfd: int, sig: int, siginfo: None = None, flags: int = ..., /) -> None: ...
+    def pidfd_send_signal(pidfd: int, sig: int, siginfo: None = None, flags: int = 0, /) -> None: ...