perf evsel: Do not use globals in config()

Instead receive a callchain_param pointer to configure callchain
aspects, not doing so if NULL is passed.

This will allow fine grained control over which evsels in an evlist
gets callchains enabled.

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-2mupip6khc92mh5x4nw9to82@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/openat-syscall-tp-fields.c

@@ -44,7 +44,7 @@ int test__syscall_openat_tp_fields(int subtest __maybe_unused)
 		goto out_delete_evlist;
 	}
 
-	perf_evsel__config(evsel, &opts);
+	perf_evsel__config(evsel, &opts, NULL);
 
 	thread_map__set_pid(evlist->threads, 0, getpid());