This commit rewrites the majority of vulkan.c to enable its use
as a general-purpose high-level utility code, usable for decoding,
encoding, and filtering of video frames.
The dependency system was rewritten to simplify management of
execution.
The image handling system was rewritten to accomodate multiplane
images.
Due to how related all the new features were, this is a single
commit.
Validation layer is an indispensable part of developing on Vulkan.
The following commands is on how to enable validation layers:
ffmpeg -init_hw_device vulkan=0,debug=1,validation_layers=VK_LAYER_LUNARG_monitor+VK_LAYER_LUNARG_api_dump
Signed-off-by: Wu Jianhua <jianhua.wu@intel.com>