Add tornado.process (#1870)

third_party/2/tornado/process.pyi

@@ -0,0 +1,24 @@
+from typing import Any, Optional
+
+long = int
+CalledProcessError: Any
+
+def cpu_count() -> int: ...
+def fork_processes(num_processes, max_restarts: int = ...) -> Optional[int]: ...
+def task_id() -> int: ...
+
+class Subprocess:
+    STREAM: Any = ...
+    io_loop: Any = ...
+    stdin: Any = ...
+    stdout: Any = ...
+    stderr: Any = ...
+    proc: Any = ...
+    returncode: Any = ...
+    def __init__(self, *args, **kwargs) -> None: ...
+    def set_exit_callback(self, callback): ...
+    def wait_for_exit(self, raise_error: bool = ...): ...
+    @classmethod
+    def initialize(cls, io_loop: Optional[Any] = ...): ...
+    @classmethod
+    def uninitialize(cls): ...