[XFS] When compiling with gcc 4.0 and CONFIG_SMP unset, there are many

warnings along the lines: xfs_linux.h:103:5: warning: "CONFIG_SMP" is not
defined. 

SGI-PV: 946630
SGI-Modid: xfs-linux-melb:xfs-kern:25171a

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nathan Scott <nathans@sgi.com>