We now enumerate all IVSHMEM devices, sort them based on PCI bus, slot,
and function numbers, then index from the resulting order. This should
be consistent across boots.
To help the user identify the correct IVSHMEM device, we also print the
list of IVSHMEM devices on startup.
This makes it a compile-time error to call a function that semantically
takes no parameters with a nonzero number of arguments.
Previously, such code would still compile, but risk blowing up the stack
if a compiler chose to use something other than caller-cleanup calling
conventions.
