selftests/bpf: Also print test name in subtest status message

This patch add test name in subtest status message line, making it possible to
grep ':OK' in the output to generate a list of passed test+subtest names, which
can be processed to generate argument list to be used with "-a", "-d" exact
string matching.

Example:

 #1/1 align/mov:OK
 ..
 #1/12 align/pointer variable subtraction:OK
 #1 align:OK
Signed-off-by: Yucong Sun <fallentree@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817044732.3263066-4-fallentree@fb.com

tools/testing/selftests/bpf/test_progs.c

@@ -150,8 +150,8 @@ void test__end_subtest()
 
 	dump_test_log(test, sub_error_cnt);
 
-	fprintf(env.stdout, "#%d/%d %s:%s\n",
-	       test->test_num, test->subtest_num, test->subtest_name,
+	fprintf(env.stdout, "#%d/%d %s/%s:%s\n",
+	       test->test_num, test->subtest_num, test->test_name, test->subtest_name,
 	       sub_error_cnt ? "FAIL" : (test->skip_cnt ? "SKIP" : "OK"));
 
 	if (sub_error_cnt)