perf trace: Avoid global perf_env with evsel__env

There is no session in perf trace unless in replay mode, so in host
mode no session can be associated with the evlist. If the evsel__env
call fails resort to the host_env that's part of the trace. Remove
errno_to_name as it becomes a called once 1-line function once the
argument is turned into a perf_env, just call perf_env__arch_strerrno
directly.

Signed-off-by: Ian Rogers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/builtin-trace.c

···
 	return sample__fprintf_callchain(sample, 38, print_opts, get_tls_callchain_cursor(), symbol_conf.bt_stop_list, trace->output);
 }
 
-static const char *errno_to_name(struct evsel *evsel, int err)
-{
-	struct perf_env *env = evsel__env(evsel);
-
-	return perf_env__arch_strerrno(env, err);
-}
-
 static int trace__sys_exit(struct trace *trace, struct evsel *evsel,
 			   union perf_event *event __maybe_unused,
 			   struct perf_sample *sample)
···
 	} else if (ret < 0) {
 errno_print: {
 		char bf[STRERR_BUFSIZE];
-		const char *emsg = str_error_r(-ret, bf, sizeof(bf)),
-			   *e = errno_to_name(evsel, -ret);
+		struct perf_env *env = evsel__env(evsel) ?: &trace->host_env;
+		const char *emsg = str_error_r(-ret, bf, sizeof(bf));
+		const char *e = perf_env__arch_strerrno(env, err);
 
 		fprintf(trace->output, "-1 %s (%s)", e, emsg);
 	}