* Makefile.in (DLL_OFILES): Add posix_ipc.o.

	* Makefile.in (DLL_OFILES): Add posix_ipc.o.
	* cygwin.din (mq_close): Export.
	(mq_getattr): Export.
	(mq_notify): Export.
	(mq_open): Export.
	(mq_receive): Export.
	(mq_send): Export.
	(mq_setattr): Export.
	(mq_timedreceive): Export.
	(mq_timedsend): Export.
	(mq_unlink): Export.
	* posix_ipc.cc: New file implementing the above functions.  Move
	shm_open and shm_unlink from syscalls.cc here.
	* sysconf.cc (sca): Set value of _SC_MQ_OPEN_MAX to MQ_OPEN_MAX,
	_SC_MQ_PRIO_MAX to MQ_PRIO_MAX, _SC_MESSAGE_PASSING to
	_POSIX_MESSAGE_PASSING.
	* include/limits.h (MQ_OPEN_MAX): Define.
	(MQ_PRIO_MAX): Define.
	* include/mqueue.h: New file.
	* include/cygwin/version.h: Bump API minor number.