xen: Add export.h for THIS_MODULE/EXPORT_SYMBOL to various xen users.

Things like THIS_MODULE and EXPORT_SYMBOL were simply everywhere
because module.h was also everywhere.  But we are fixing the latter.
So we need to call out the real users in advance.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

drivers/xen/manage.c

@@ -9,6 +9,7 @@
 #include <linux/stop_machine.h>
 #include <linux/freezer.h>
 #include <linux/syscore_ops.h>
+#include <linux/export.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>

drivers/xen/swiotlb-xen.c

@@ -35,6 +35,7 @@
 
 #include <linux/bootmem.h>
 #include <linux/dma-mapping.h>
+#include <linux/export.h>
 #include <xen/swiotlb-xen.h>
 #include <xen/page.h>
 #include <xen/xen-ops.h>

drivers/xen/xenbus/xenbus_client.c

@@ -33,6 +33,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/vmalloc.h>
+#include <linux/export.h>
 #include <asm/xen/hypervisor.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/event_channel.h>

drivers/xen/xenbus/xenbus_probe_backend.c

@@ -42,6 +42,7 @@
 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/notifier.h>
+#include <linux/export.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>