[XFS] fix non-smp xfs build

xfs_reserve_blocks() calls xfs_icsb_sync_counters_locked(), which is not
defined if !CONFIG_SMP/!HAVE_PERCPU_SB

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30991a
Signed-off-by: NEric Sandeen <sandeen@sandeen.net>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

fs/xfs/xfs_mount.h

@@ -217,6 +217,7 @@ extern void	xfs_icsb_sync_counters_locked(struct xfs_mount *, int);
 #define xfs_icsb_init_counters(mp)	(0)
 #define xfs_icsb_reinit_counters(mp)	do { } while (0)
 #define xfs_icsb_sync_counters(mp, flags)	do { } while (0)
+#define xfs_icsb_sync_counters_locked(mp, flags) do { } while (0)
 #endif
 
 typedef struct xfs_ail {