doc: Remove old changelog fragments

doc/changes/auxiliary/mr.358.md

-os/threading: Include `xrt_compiler.h` to fix missing stdint types.

doc/changes/auxiliary/mr.359.1.md

-util: Add a very simple fifo for indices, this is used to keep track of
-swapchain in order of age (oldness).

doc/changes/auxiliary/mr.359.2.md

-util: Expand `u_hashset` to be able to automatically allocate a `u_hashet_item`
-and insert it.
\ No newline at end of file

doc/changes/big/mr.408.md

----
-- mr.408
-- mr.409
----
-Centralise the logging functionality in Monado to a single util helper.
-Previously most of our logging was done via fprints and gated behind booleans,
-now there are common functions to call and a predfined set of levels.

doc/changes/compositor/mr.358.md

-main: Include `<math.h>` in layers renderer for missing `tanf` function.

doc/changes/compositor/mr.359.1.md

-swapchain: Give out the oldset image index when a image is acquired. This logic
-can be made better, but will work for the good case.

doc/changes/compositor/mr.359.2.md

-swapchain: Close any FDs that are still valid, for instance the ipc server
-copies the FDs to the client.

doc/changes/compositor/mr.359.3.md

-client: When we give a image fd to the either OpenGL or Vulkan it is consumed
-and can not be rused. So make sure that it is set to an invalid fd value on the
-`xrt_image_fd` on the owning `xrt_swapchain_fd`.

doc/changes/compositor/mr.394.1.md

-main: We were alpha blending all layers previously, but now we support the
-layer flag that OpenXR gives us. We do this by using different `VkImageView`s
-with different component swizzles.

doc/changes/compositor/mr.394.2.md

-layer_rendering: Use the visibility flags on quad to correctly show the layers
-in each eye.

doc/changes/drivers/mr.359.md

-psvr: Normalize the rotation to not trip up the client app when it gives the
-rotation back to `st/oxr` again.

doc/changes/drivers/mr.405.md

-vive: Create vive_config module to isolate config code and avoid duplication between controller and headset code.
-vive: Probe for controllers in vive_proper interface.
-vive: Fix a bug where using the Vive Pro crashed Monado.
-vive: Fix a bug where the controller didn't parse JSON vectors correctly.
-vive: Move missing functions to and use u_json.

doc/changes/drivers/mr.406.md

-vive: Add support for Gen1 and Gen2 Vive Trackers.

doc/changes/drivers/mr.417.md

-vive: Port to new u_logging API.

doc/changes/drivers/mr.418.md

-comp: Set a compositor window title.

doc/changes/ipc/mr.359.1.md

-server: Almost completely overhaul the handling of swapchain life cycle
-including: correctly track which swapchains are alive; reuse ids; enforce the
-maximum number of swapchains; and destroy underlying swapchains when they are
-destroyed by the client.

doc/changes/ipc/mr.359.2.md

-util: Make sure to not access NULL control messages, say in the case of the
-server failing to create a swapchain. Also add a whole bunch of paranoia when
-it comes to the alignment of the control message buffers.

doc/changes/ipc/mr.369.md

-ipc: Return XR_ERROR_INSTANCE_LOST on IPC errors.

doc/changes/misc_features/mr.330.md

-build: Allow enabling inter-procedural optimization in CMake GUIs, if supported by platform and compiler.

doc/changes/state_trackers/mr.358.md

-OpenXR: Update headers to 1.0.9.