perf strlist: load() should return a negative errno

To match what its users return.

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>
Link: http://lkml.kernel.org/n/tip-jntpe2lwg1fxn1bku7uccan0@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/strlist.c

@@ -72,7 +72,7 @@ int strlist__load(struct strlist *slist, const char *filename)
 	FILE *fp = fopen(filename, "r");
 
 	if (fp == NULL)
-		return errno;
+		return -errno;
 
 	while (fgets(entry, sizeof(entry), fp) != NULL) {
 		const size_t len = strlen(entry);