client API: declare mpv_suspend/mpv_resume deprecated

They're useless, and I have no idea what they're actually supposed to do
(wrt. pending input processing changes).

Also remove their implicit uses from the IPC handlers.

DOCS/client-api-changes.rst

@@ -39,6 +39,8 @@ API changes
           mpv_initialize().
         - do not override the SIGPIPE signal handler anymore. This was done as
           workaround for the FFmpeg TLS code, which has been fixed long ago.
+        - deprecate mpv_suspend() and mpv_resume(). They will be stubbed out
+          in mpv 0.22.0.
  --- mpv 0.19.0 ---
  1.22   - add stream_cb API for custom protocols
  --- mpv 0.18.1 ---

DOCS/interface-changes.rst

@@ -63,6 +63,11 @@ Interface changes
       treating it as a hardware overlay (without applying GL filtering). Also
       to be changed in 0.22.0: the --fs flag will be reset to "no" by default
       (like on the other platforms).
+    - deprecate "resume" and "suspend" IPC commands. They will be completely
+      removed in 0.22.0.
+    - deprecate mp.suspend(), mp.resume(), mp.resume_all() Lua scripting
+      commands, as well as setting mp.use_suspend. They will be completely
+      removed in 0.22.0.
     - add almost all options to the property list, meaning you can change
       options without adding "options/" to the property name (a new section
       has been added to the manpage describing some conflicting behavior

DOCS/man/ipc.rst

@@ -242,12 +242,16 @@ extra commands can also be used as part of the protocol:
     command.
 
 ``suspend``
+    Deprecated, will be removed completely in 0.21.0.
+
     Suspend the mpv main loop. There is a long-winded explanation of this in
     the C API function ``mpv_suspend()``. In short, this prevents the player
     from displaying the next video frame, so that you don't get blocked when
     trying to access the player.
 
 ``resume``
+    Deprecated, will be removed completely in 0.21.0.
+
     Undo one ``suspend`` call. ``suspend`` increments an internal counter, and
     ``resume`` decrements it. When 0 is reached, the player is actually resumed.