Perf report is demangling symbols but not annotate.

The former uses internal demangling via libbdf or libiberty. The latter
executes objdump which by default does not demangle symbols.

This patch adds the -C option to the objdump cmdline to enable symbol
demangling.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4c07b323.2126e30a.6245.0e1e@mx.google.com>
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>