util/meson.build: fix fdmon-io_uring build

util/meson.build: fix fdmon-io_uring build

libqemuutil.a build fails with this error:

  /usr/bin/ld: libqemuutil.a(util_fdmon-io_uring.c.o): in function `get_sqe':
  qemu/build/../util/fdmon-io_uring.c:83: undefined reference to `io_uring_get_sqe'
  /usr/bin/ld: qemu/build/../util/fdmon-io_uring.c:92: undefined reference to `io_uring_submit'
  /usr/bin/ld: qemu/build/../util/fdmon-io_uring.c:96: undefined reference to `io_uring_get_sqe'
  /usr/bin/ld: libqemuutil.a(util_fdmon-io_uring.c.o): in function `fdmon_io_uring_wait':
  qemu/build/../util/fdmon-io_uring.c:289: undefined reference to `io_uring_submit_and_wait'
  /usr/bin/ld: libqemuutil.a(util_fdmon-io_uring.c.o): in function `fdmon_io_uring_setup':
  qemu/build/../util/fdmon-io_uring.c:328: undefined reference to `io_uring_queue_init'
  /usr/bin/ld: libqemuutil.a(util_fdmon-io_uring.c.o): in function `fdmon_io_uring_destroy':
  qemu/build/../util/fdmon-io_uring.c:343: undefined reference to `io_uring_queue_exit'
  collect2: error: ld returned 1 exit status

This patch fix the issue adding 'linux_io_uring' dependency for
fdmon-io_uring.c

Fixes: a81df1b68b ("libqemuutil, qapi, trace: convert to meson")
Cc: pbonzini@redhat.com
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20200821154853.94379-1-sgarzare@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>