perf tools: Modify error code for when perf_session__new() fails

Because perf_session__new() can fail for more reasons than just ENOMEM,
modify error code(ENOMEM or EINVAL) to -1.

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1411522417-9917-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c
index 2376218..f295141 100644
--- a/tools/perf/builtin-kmem.c
+++ b/tools/perf/builtin-kmem.c
@@ -698,7 +698,7 @@
 
 	session = perf_session__new(&file, false, &perf_kmem);
 	if (session == NULL)
-		return -ENOMEM;
+		return -1;
 
 	symbol__init(&session->header.env);