liburing: bump to 0.1 tag + some extra patches

Normally changing the version of the tag in this manner would be nasty
for users -- `nix-env -u` would not see this as an upgrade on the
channel, for instance, if you had a previous version installed. But
liburing is a *library* and does not really come included with any
useful end-user tools. Most cases will use it directly as a build
dependency, in which case, an appropriate rebuild will happen anyway.

This also re-introduces AArch64 builds, which was previously broken due
to some internal changes requiring memory barrier support. In a twist of
fate, however, this was later broken by another patch, which was written
to fix a *different* regression for users. So we simply apply both of
these patches, as well as a third patch that re-fixes AArch64 support,
which I will submit upstream to Jens. Life is never easy.

Signed-off-by: Austin Seipp <aseipp@pobox.com>