perf tools: Demangle kernel and kernel module symbols too

Some kernels contain C++ code, and thus their symbols need to be
demangled.  This allows 'perf kvm top' to generate readable output.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/26f71bf5bf7ee1408e3f1a803556d5df18223ef1.1390420726.git.avi@cloudius-systems.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>