xen: add missing include

xen-all needs to access CharDeviceState's filename field, so
it needs to include char/char.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

xen-all.c

diff --git a/xen-all.c b/xen-all.c
index 50edaec..19bcfd1 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -16,6 +16,7 @@
 #include "hw/xen_backend.h"
 #include "qmp-commands.h"
 
+#include "char/char.h"
 #include "qemu/range.h"
 #include "sysemu/xen-mapcache.h"
 #include "trace.h"