Turns out that neither PowerPC nor older x86 compilers know this switch
...

and since it does not make a measurable difference, just omit it.
Reported-by: Paul Mackerras <paulus@samba.org>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>