Fixed the following bugs:
1. Message priority was not set at all at two places
2. Limits check was not correct while returning error values
3. We are suppose to allow multiple users operate on the same queue
using a named descriptor. However any one user calling close before
the other would result in closing the queue even when other users
might be using it. Track number of users and close only if number of
users is zero. Yet to do functional tests for this, so this is untested,
but introduce it anyway at this juncture.
Implement message queues support for Minix.
Pending tasks:
Blocking or non blocking for send receive?
Sort by priority and time?
Test codes?
Bug fixes?
Sanchayan Maity