Log message:
liburing: Require a c11 compiler for stdatomic.

Log message:
liburing: import new package, version 2.3

This is the Linux io_uring library, liburing. liburing provides helpers to
set up and tear down io_uring instances, and also a simplified interface
for applications that don't need (or want) to deal with the full kernel-
side implementation.

Packaged in wip by Alexander Schreiber. Minor adjustments by myself, also
build tested on Fedora 37.