A build error happens in alpine CI when linux/errqueue.h is included
in io/channel-socket.c, due to redefining of 'struct __kernel_timespec':

===
ninja: job failed: [...]
In file included from /usr/include/linux/errqueue.h:6,
                 from ../io/channel-socket.c:29:
/usr/include/linux/time_types.h:7:8: error: redefinition of 'struct __kernel_timespec'
    7 | struct __kernel_timespec {
      |        ^~~~~~~~~~~~~~~~~
In file included from /usr/include/liburing.h:19,
                 from /builds/user/qemu/include/block/aio.h:18,
                 from /builds/user/qemu/include/io/channel.h:26,
                 from /builds/user/qemu/include/io/channel-socket.h:24,
                 from ../io/channel-socket.c:24:
/usr/include/liburing/compat.h:9:8: note: originally defined here
    9 | struct __kernel_timespec {
      |        ^~~~~~~~~~~~~~~~~
ninja: subcommand failed
===

As above error message suggests, 'struct __kernel_timespec' was already
defined by liburing/compat.h.

Fix alpine CI by adding test to disable liburing in configure step if a
redefinition happens between linux/errqueue.h and liburing/compat.h.

[dgilbert: This has been fixed in Alpine issue 13813 and liburing]

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220513062836.965425-2-leobras@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>