perf evsel: Introduce fprintf_callchain() method out of fprintf_sym()

perf evsel: Introduce fprintf_callchain() method out of fprintf_sym()

In 'perf trace' we're just interested in printing callchains, and we
don't want to use the symbol_conf.use_callchain, so move the callchain
part to a new method.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kcn3romzivcpxb3u75s9nz33@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>