Add linux-headers to QEMU_INCLUDES

virtio/dataplane/vring.c requires the Linux headers and is built for all
targets. So we need to add the corresponding include to QEMU_INCLUDES to
avoid that outdated distribution headers are used.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/configure b/configure
index 73df181..258c82a 100755
--- a/configure
+++ b/configure
@@ -544,6 +544,7 @@
   if [ "$cpu" = "i386" -o "$cpu" = "x86_64" ] ; then
     audio_possible_drivers="$audio_possible_drivers fmod"
   fi
+  QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers $QEMU_INCLUDES"
 ;;
 esac
 
@@ -4227,10 +4228,6 @@
 fi
 includes="-I\$(SRC_PATH)/tcg $includes"
 
-if test "$linux" = "yes" ; then
-  includes="-I\$(SRC_PATH)/linux-headers $includes"
-fi
-
 for i in $ARCH $TARGET_BASE_ARCH ; do
   case "$i" in
   alpha)