This commit add helpers to create and to import a DmaBuf via the
external_dmabuf_info struct.
The import path is based on the image creation of wlroots and the create path is
inspired by the wlroots vulkan allocator MR.
vulkan_wait_idle waits until the device is idle and all referenced
objects can be destroyed.
vulkan_wait_fence waits until a fence is triggered by a finished
queueSubmit.
vulkan: wait on fence
This commit should just shuffle code around with no functional changes.
The goal is to ease development of simple vulkan nodes by providing
generic helpers.
Mark some structures, arrays static/const at various places.
In some cases this prevents unnecessary initialization
when a function is entered.
All in all, the text segments across all shared
libraries are reduced by about 2 KiB. However,
the total size increases by about 2 KiB as well.
