Use proper casting (mqd_t)-1 to check for invalid values of mqd_t.
Use proper casting (mqd_t)-1 to check for invalid values of mqd_t.

Comparison with zero is undefined, but the (mqd_t)-1 constant value is
defined as error condition by POSIX.

lscube/feng,winlinvip/feng,winlinvip/feng,lscube/feng,lscube/feng,winlinvip/feng