Add os.splice and flags on Linux for Python 3.10+ (#10771)

stdlib/os/__init__.pyi

@@ -1062,9 +1062,20 @@ if sys.version_info >= (3, 10) and sys.platform == "linux":
     EFD_CLOEXEC: int
     EFD_NONBLOCK: int
     EFD_SEMAPHORE: int
+    SPLICE_F_MORE: int
+    SPLICE_F_MOVE: int
+    SPLICE_F_NONBLOCK: int
     def eventfd(initval: int, flags: int = 524288) -> FileDescriptor: ...
     def eventfd_read(fd: FileDescriptor) -> int: ...
     def eventfd_write(fd: FileDescriptor, value: int) -> None: ...
+    def splice(
+        src: FileDescriptor,
+        dst: FileDescriptor,
+        count: int,
+        offset_src: int | None = ...,
+        offset_dst: int | None = ...,
+        flags: int = 0,
+    ) -> int: ...
 
 if sys.version_info >= (3, 12) and sys.platform == "linux":
     CLONE_FILES: int