bpf: selftest: Move sock_fields test into test_progs

This is a mechanical change to
1. move test_sock_fields.c to prog_tests/sock_fields.c
2. rename progs/test_sock_fields_kern.c to progs/test_sock_fields.c

Minimal change is made to the code itself.  Next patch will make
changes to use new ways of writing test, e.g. use skel and global
variables.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200925000427.3857814-1-kafai@fb.com

tools/testing/selftests/bpf/.gitignore

@@ -13,7 +13,6 @@ test_verifier_log
 feature
 test_sock
 test_sock_addr
-test_sock_fields
 urandom_read
 test_sockmap
 test_lirc_mode2_user

tools/testing/selftests/bpf/Makefile

@@ -35,7 +35,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_verifier_log test_dev_cgroup test_tcpbpf_user \
 	test_sock test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage \
-	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl \
+	test_netcnt test_tcpnotify_user test_sysctl \
 	test_progs-no_alu32 \
 	test_current_pid_tgid_new_ns
 

tools/testing/selftests/bpf/prog_tests/sock_fields.c

@@ -409,10 +409,10 @@ static void test(void)
 	check_result();
 }
 
-int main(int argc, char **argv)
+void test_sock_fields(void)
 {
 	struct bpf_prog_load_attr attr = {
-		.file = "test_sock_fields_kern.o",
+		.file = "test_sock_fields.o",
 		.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
 		.prog_flags = BPF_F_TEST_RND_HI32,
 	};
@@ -477,6 +477,4 @@ int main(int argc, char **argv)
 	cleanup_cgroup_environment();
 
 	printf("PASS\n");
-
-	return 0;
 }