configure: fix trace backend check

Found thanks to shellcheck!

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/configure b/configure
index 83b40fc906448bef43fe9a6faf5941a08c015b1a..44ac9abc7e082c66a938f464f36e174dcd9a6723 100755 (executable)
--- a/configure
+++ b/configure
@@ -4817,7 +4817,7 @@ echo "libcap-ng support $cap_ng"
 echo "vhost-net support $vhost_net"
 echo "vhost-scsi support $vhost_scsi"
 echo "Trace backends    $trace_backends"
-if test "$trace_backend" = "simple"; then
+if have_backend "simple"; then
 echo "Trace output file $trace_file-<pid>"
 fi
 if test "$spice" = "yes"; then