perf test: Print if shell directory isn't present

If the shell test directory isn't present the exit code will be 255 but
with no error messages printed. Add an error message.

Signed-off-by: Ian Rogers <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: captain5050

tools/perf/tests/builtin-test.c

@@ -543,8 +543,11 @@ static int run_shell_tests(int argc, const char *argv[], int i, int width)
 		return -1;
 
 	dir = opendir(st.dir);
-	if (!dir)
+	if (!dir) {
+		pr_err("failed to open shell test directory: %s\n",
+			st.dir);
 		return -1;
+	}
 
 	for_each_shell_test(dir, st.dir, ent) {
 		int curr = i++;