sparse irqs: add irqnr.h to the user headers list

Impact: fix build error

/home/mingo/tip/usr/include/linux/random.h:11: included file
'linux/irqnr.h' is not exported
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/Kbuild

@@ -313,6 +313,7 @@ unifdef-y += ptrace.h
 unifdef-y += qnx4_fs.h
 unifdef-y += quota.h
 unifdef-y += random.h
+unifdef-y += irqnr.h
 unifdef-y += reboot.h
 unifdef-y += reiserfs_fs.h
 unifdef-y += reiserfs_xattr.h