perf tools: Use normalized arch name for searching objdump path

perf tools: Use normalized arch name for searching objdump path

David reported that perf report for i686 target data on x86_64 host
failed to work because it tried to find out cross-compiled objdump.

However objdump for x86_64 is compatible to i686 so that it doesn't need
to do it at all.  To prevent similar artifacts, normalize arch name when
comparing host and file architectures.

Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Tested-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Irina Tirdea <irina.tirdea@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1351835406-15208-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>