Under normal operations, a framebuffer is created with each VkImageView
it will need to use. This extension allows users to specify a flag that
tells the driver to wait until render pass begin time. The user must
also request this feature during device creation, this behavior is not
enabled by default.

Bug: b/167223759
Tests: dEQP-VK.imageless_framebuffer.*
Change-Id: I2be5cec4d8174e20372eb9e148a05034dd338341
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48488Tested-by: Sean Risser <srisser@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>