libvduse: Switch to unsigned int for inuse field in struct VduseVirtq

libvduse: Switch to unsigned int for inuse field in struct VduseVirtq

It seems there is no need to keep the inuse field signed and end up with
compiler warnings for sign-compare.

  CC       libvduse.o
libvduse.c: In function ‘vduse_queue_pop’:
libvduse.c:789:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
  789 |     if (vq->inuse >= vq->vring.num) {
      |                   ^~

Instead of casting the comparison to unsigned int, just make the inuse
field unsigned int in the fist place.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <9fe3fd8b042e048bd04d506ca6e43d738b5c45b7.1671741278.git.marcel@holtmann.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>