perf: Turn off compiler warnings for flex and bison generated files

We don't know what types of warnings different versions of flex
and bison combined with different versions of gcc is going to
generate, so just punt and don't warn about anything.

This fixes the build of perf for me on an openSUSE 12.1 system.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20120504183254.GA11154@kroah.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>