xen: link against xentoolcore

Xen libraries in 4.10 include a new xentoolcore library.  This
contains the xentoolcore_restrict_all function which we are about to
want to use.
Signed-off-by: NIan Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: NStefano Stabellini <sstabellini@kernel.org>

configure

@@ -2189,6 +2189,9 @@ if test "$xen" != "no" ; then
     xen=yes
     xen_pc="xencontrol xenstore xenguest xenforeignmemory xengnttab"
     xen_pc="$xen_pc xenevtchn xendevicemodel"
+    if $pkg_config --exists xentoolcore; then
+      xen_pc="$xen_pc xentoolcore"
+    fi
     QEMU_CFLAGS="$QEMU_CFLAGS $($pkg_config --cflags $xen_pc)"
     libs_softmmu="$($pkg_config --libs $xen_pc) $libs_softmmu"
     LDFLAGS="$($pkg_config --libs $xen_pc) $LDFLAGS"
@@ -2220,18 +2223,20 @@ EOF
         cat > $TMPC <<EOF &&
 #undef XC_WANT_COMPAT_MAP_FOREIGN_API
 #include <xenforeignmemory.h>
+#include <xentoolcore.h>
 int main(void) {
   xenforeignmemory_handle *xfmem;
 
   xfmem = xenforeignmemory_open(0, 0);
   xenforeignmemory_map2(xfmem, 0, 0, 0, 0, 0, 0, 0);
+  xentoolcore_restrict_all(0);
 
   return 0;
 }
 EOF
-        compile_prog "" "$xen_libs -lxendevicemodel $xen_stable_libs"
+        compile_prog "" "$xen_libs -lxendevicemodel $xen_stable_libs -lxentoolcore"
       then
-      xen_stable_libs="-lxendevicemodel $xen_stable_libs"
+      xen_stable_libs="-lxendevicemodel $xen_stable_libs -lxentoolcore"
       xen_ctrl_version=41000
       xen=yes
     elif