memory: Rename queue to mrqueue (memory region queue)

SunOS declares struct queue in <netinet/in.h>.

This fixes build on SmartOS (Joyent).

Patch cherry-picked from pkgsrc by jperkin (Joyent).

Signed-off-by: Kamil Rytarowski <n54@gmx.com>
Message-Id: <20170903163304.17919-1-n54@gmx.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>