Add zone_get_hostid() function

Minimal support added for the zone_get_hostid() function.  Only
global zones are supported therefore this function must be called
with a NULL argumment.  Additionally, I've added the HW_HOSTID_LEN
define and updated all instances where a hard coded magic value
of 11 was used; "A good riddance of bad rubbish!"

include/sys/proc.h

@@ -33,6 +33,7 @@
 #include <linux/sysctl.h>
 #include <linux/seq_file.h>
 #include <sys/sysmacros.h>
+#include <sys/systeminfo.h>
 #include <sys/kmem.h>
 #include <sys/mutex.h>
 #include <sys/kstat.h>

include/sys/sysmacros.h

@@ -143,6 +143,7 @@ extern int p0;
 
 /* Missing misc functions */
 extern int highbit(unsigned long i);
+extern uint32_t zone_get_hostid(void *zone);
 
 #define makedevice(maj,min) makedev(maj,min)
 

include/sys/systeminfo.h

@@ -1,4 +1,9 @@
 #ifndef _SPL_SYSTEMINFO_H
 #define _SPL_SYSTEMINFO_H
 
+#define HW_INVALID_HOSTID	0xFFFFFFFF	/* an invalid hostid */
+#define HW_HOSTID_LEN		11		/* minimum buffer size needed */
+						/* to hold a decimal or hex */
+						/* hostid string */
+
 #endif /* SPL_SYSTEMINFO_H */