* Update release number to 124.
Github Issues:
* Fix Makefile SPECREMARK macro to work when not building in a git tree
(public issue 992).
* Ignore pname:aspectMask for unused attachments in
slink:VkSubpassDescription2KHR valid usage statements (public pull
request 1028).
* Minor markup / spelling fixes (public pull requests 1035, 1045).
Internal Issues:
* Fix markup in Valid Usage statement for slink:VkCreateFramebuffer
(internal issue 1823).
* Add a new <<synchronization-signal-operation-order, _signal operation
order_>> section to the synchronization chapter which describes in
detail the ordering guarantees provided by the API between fence and
semaphore signal operations (internal merge request 3368).
* Move generated `appendix/meta/` files into the Makefile GENERATED
directory (internal merge request 3381).
New Extensions
* `<<VK_KHR_shader_clock>>`
* `<<VK_KHR_timeline_semaphore>>`
* Update release number to 105.
Public Issues:
* Fix contractions and other markup issues (public pull request 935).
New Extensions:
* Google Games Platform
** New `ggp` platform and associated header file `vulkan_ggp.h`
** `VK_GGP_frame_token`
** `VK_GGP_stream_descriptor_surface`
