kmemtrace, fs: fix linux/fdtable.h header file dependencies

Impact: cleanup

We want to remove percpu.h from rcupdate.h (for upcoming kmemtrace
changes), but this is not possible currently without breaking the
build because fdtable.h has an implicit include file dependency: it
uses __init does not include init.h.

This can cause build failures on non-x86 architectures:

 /home/mingo/tip/include/linux/fdtable.h:66: error: expected '=', ',',
 ';', 'asm' or '__attribute__' before 'files_defer_init'
 make[2]: *** [fs/locks.o] Error 1

We got this header included indirectly via rcupdate.h's percpu.h
inclusion - but if that is not there the build will break.

Fix it.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: paulmck@linux.vnet.ibm.com
LKML-Reference: <1237898630.25315.83.camel@penberg-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>