Minor fix to configure on s390x

configure on s390x has a key check fail with an error about
a variable being used uninitialized. So let's initialize it.

Signed-off-by: Rich Ercolani <[email protected]>

Author: rincebrain

config/kernel-bdi.m4

@@ -6,11 +6,14 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BDI], [
 		#include <linux/fs.h>
 		struct super_block sb;
 	], [
-		char *name = "bdi";
-		atomic_long_t zfs_bdi_seq;
-		int error __attribute__((unused)) =
-		    super_setup_bdi_name(&sb, "%.28s-%ld", name,
-		    atomic_long_inc_return(&zfs_bdi_seq));
+
+                char *name = "bdi";
+                atomic_long_t zfs_bdi_seq;
+                int error __attribute__((unused));
+                atomic_long_set(&zfs_bdi_seq, 0);
+                error =
+                    super_setup_bdi_name(&sb, "%.28s-%ld", name,
+                    atomic_long_inc_return(&zfs_bdi_seq));
 	])
 
 	ZFS_LINUX_TEST_SRC([bdi_setup_and_register], [