uapi: mqueue.h: add missing linux/types.h include

Commit 63159f5dcccb ("uapi: Use __kernel_long_t in struct mq_attr")
changed the types from long to __kernel_long_t, but didn't add a
linux/types.h include. Code that tries to include this header directly
breaks:

/usr/include/linux/mqueue.h:26:2: error: unknown type name '__kernel_long_t'
__kernel_long_t mq_flags; /* message queue flags */

This also upsets configure tests for this header:

checking linux/mqueue.h usability... no
checking linux/mqueue.h presence... yes
configure: WARNING: linux/mqueue.h: present but cannot be compiled
configure: WARNING: linux/mqueue.h: check for missing prerequisite headers?
configure: WARNING: linux/mqueue.h: see the Autoconf documentation
configure: WARNING: linux/mqueue.h: section "Present But Cannot Be Compiled"
configure: WARNING: linux/mqueue.h: proceeding with the compiler's result
checking for linux/mqueue.h... no

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Mike Frysinger <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/uapi/linux/mqueue.h

···
 #ifndef _LINUX_MQUEUE_H
 #define _LINUX_MQUEUE_H
 
+#include <linux/types.h>
+
 #define MQ_PRIO_MAX 	32768
 /* per-uid limit of kernel memory used by mqueue, in bytes */
 #define MQ_BYTES_MAX	819200