xenstore: Use <xenstore.h>

In the next release of Xen (4.2), xs.h became deprecated.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
diff --git a/configure b/configure
index b68c0ca..c4e4960 100755
--- a/configure
+++ b/configure
@@ -1381,7 +1381,7 @@
   elif (
       cat > $TMPC <<EOF
 #include <xenctrl.h>
-#include <xs.h>
+#include <xenstore.h>
 #include <stdint.h>
 #include <xen/hvm/hvm_info_table.h>
 #if !defined(HVM_MAX_VCPUS)