libmpathutil: udev: prevent interruption by thread cancellation

Using mutexes only guarantees no concurrency during normal runtime.
However, if a thread is cancelled mid-execution, a libudev API call
might be interrupted halfway (partially executed), leaving memory
values in an inconsistent or abnormal state.

Furthermore, this change aligns with the requirement that libudev
interfaces are not thread-safe and must not be called from multiple
threads.

Signed-off-by: Wu Guanghao <wuguanghao3@huawei.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>

Author: wuguanghao3