block/gluster: Add missing argument to qemu_gluster_init() call

Commit adccfbcd6020e928db93b2b4faf0dbd05ffbe016 (block: gluster - add
reopen support.) did not supply the qemu_gluster_init() Error **
argument, needed since commit a7451cb850d115f257080aff3fbc54f255ebf8f7
(gluster: correctly propagate errors).

Pass through qemu_gluster_reopen_prepare()'s errp, as done in
qemu_gluster_open().

Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/gluster.c

diff --git a/block/gluster.c b/block/gluster.c
index 54ee9b7..fe7a10c 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -364,7 +364,7 @@
 
     gconf = g_malloc0(sizeof(GlusterConf));
 
-    reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename);
+    reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename, errp);
     if (reop_s->glfs == NULL) {
         ret = -errno;
         goto exit;