xen: make it possible to build without the Xen PV domain builder

Until the previous patch this relied on xc_fd(), which was only
implemented for Xen 4.0 and earlier.

Given this wasn't working since Xen 4.0 I have marked this as disabled
by default.

Removing this support drops the use of a bunch of symbols from
libxenctrl, specifically:

  - xc_domain_create
  - xc_domain_destroy
  - xc_domain_getinfo
  - xc_domain_max_vcpus
  - xc_domain_setmaxmem
  - xc_domain_unpause
  - xc_evtchn_alloc_unbound
  - xc_linux_build

This is another step towards only using Xen libraries which provide a
stable inteface.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
diff --git a/configure b/configure
index 9ead31d..3506e44 100755
--- a/configure
+++ b/configure
@@ -250,6 +250,7 @@
 vnc_png=""
 xen=""
 xen_ctrl_version=""
+xen_pv_domain_build="no"
 xen_pci_passthrough=""
 linux_aio=""
 cap_ng=""
@@ -927,6 +928,10 @@
   ;;
   --enable-xen-pci-passthrough) xen_pci_passthrough="yes"
   ;;
+  --disable-xen-pv-domain-build) xen_pv_domain_build="no"
+  ;;
+  --enable-xen-pv-domain-build) xen_pv_domain_build="yes"
+  ;;
   --disable-brlapi) brlapi="no"
   ;;
   --enable-brlapi) brlapi="yes"
@@ -2229,6 +2234,12 @@
   fi
 fi
 
+if test "$xen_pv_domain_build" = "yes" &&
+   test "$xen" != "yes"; then
+    error_exit "User requested Xen PV domain builder support" \
+	       "which requires Xen support."
+fi
+
 ##########################################
 # libtool probe
 
@@ -4848,6 +4859,7 @@
 echo "xen support       $xen"
 if test "$xen" = "yes" ; then
   echo "xen ctrl version  $xen_ctrl_version"
+  echo "pv dom build      $xen_pv_domain_build"
 fi
 echo "brlapi support    $brlapi"
 echo "bluez  support    $bluez"
@@ -5219,6 +5231,9 @@
 if test "$xen" = "yes" ; then
   echo "CONFIG_XEN_BACKEND=y" >> $config_host_mak
   echo "CONFIG_XEN_CTRL_INTERFACE_VERSION=$xen_ctrl_version" >> $config_host_mak
+  if test "$xen_pv_domain_build" = "yes" ; then
+    echo "CONFIG_XEN_PV_DOMAIN_BUILD=y" >> $config_host_mak
+  fi
 fi
 if test "$linux_aio" = "yes" ; then
   echo "CONFIG_LINUX_AIO=y" >> $config_host_mak