[PATCH] slab: alpha inlining fix

It is essential that index_of() be inlined.  But alpha undoes the gcc
inlining hackery and index_of() ends up out-of-line.  So fiddle with things
to make that function inline again.

Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>