perf evsel: Require that callchains be resolved before calling fprintf_{sym,callchain}

perf evsel: Require that callchains be resolved before calling fprintf_{sym,callchain}

This way the print routine merely does printing, not requiring access to
the resolving machinery, which helps disentangling the object files and
easing creating subsets with a limited functionality set.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-2ti2jbra8fypdfawwwm3aee3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>