Update and add stubs for os module (#1645)

stdlib/3/posix.pyi

@@ -10,3 +10,23 @@ from typing import NamedTuple
 if sys.version_info >= (3, 3):
     uname_result = NamedTuple('uname_result', [('sysname', str), ('nodename', str),
         ('release', str), ('version', str), ('machine', str)])
+
+    times_result = NamedTuple('times_result', [
+        ('user', float),
+        ('system', float),
+        ('children_user', float),
+        ('children_system', float),
+        ('elapsed', float),
+    ])
+
+    waitid_result = NamedTuple('waitid_result', [
+        ('si_pid', int),
+        ('si_uid', int),
+        ('si_signo', int),
+        ('si_status', int),
+        ('si_code', int),
+    ])
+
+    sched_param = NamedTuple('sched_priority', [
+        ('sched_priority', int),
+    ])