Since switching to the 1.2 api as a requirement, might as well use the
relevant structs instead of extension struct (for multiview). Came up
when double-checking the max views property due to running into what
appears to be an nvidia bug where > 29 views (any bit pattern) cause a
segfault when creating the pipeline.
The stack is arbitrary strings that the validation layer debug callback
prints in reverse order after each message. This makes it easy to work
out what nodes in a pipeline/render pass plist are causing validation
errors. Still have to narrow down the actual line, but the messages seem
to help with that.
Putting qfvPushDebug/qfvPopDebug around other calls to vulkan should
help out a lot, tool.
As a bonus, the stack is printed before debug_breakpoint is called, so
it's immediately visible in gdb.
