perf annotate: Don't die() when finding an invalid config option

The perf_config() infrastructure we inherited from git calls die() when
the provided config callback returns -1, meaning some key in a config
section is unexpected, that seems ok for a stdio based tool, but in
--tui we end up messing up the output, so just tell the user about the
error, wait for a keystroke and return 0, being more resilient and
proceeding with what we managed to parse.

That die() needs to die, tho :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-pqtsffh2kwr5mwm4qg9kgotu@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/annotate.c

@@ -1152,9 +1152,9 @@ static int annotate__config(const char *var, const char *value,
 		      sizeof(struct annotate_config), annotate_config__cmp);
 
 	if (cfg == NULL)
-		return -1;
-
-	*cfg->value = perf_config_bool(name, value);
+		ui__warning("%s variable unknown, ignoring...", var);
+	else
+		*cfg->value = perf_config_bool(name, value);
 	return 0;
 }