Revert "selftests/cgroup: Drop define _GNU_SOURCE"

JIRA: https://issues.redhat.com/browse/RHEL-80382

commit a97853f
Author: Shuah Khan <skhan@linuxfoundation.org>
Date:   Thu May 16 20:22:37 2024 -0600

    Revert "selftests/cgroup: Drop define _GNU_SOURCE"

    This reverts commit c1457d9.

    The framework change to add D_GNU_SOURCE to KHDR_INCLUDES
    to Makefile, lib.mk, and kselftest_harness.h is reverted
    as it is causing build failures and warnings.

    Revert this change as this change depends on the framework
    change.

    Reported-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Radostin Stoyanov <rstoyano@redhat.com>

Author: rst0git

tools/testing/selftests/cgroup/cgroup_util.c

@@ -1,4 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
+
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/limits.h>

tools/testing/selftests/cgroup/test_core.c

@@ -1,4 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
 #include <linux/limits.h>
 #include <linux/sched.h>
 #include <sys/types.h>

tools/testing/selftests/cgroup/test_cpu.c

@@ -1,4 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
 #include <linux/limits.h>
 #include <sys/sysinfo.h>
 #include <sys/wait.h>

tools/testing/selftests/cgroup/test_hugetlb_memcg.c

@@ -1,4 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
 #include <linux/limits.h>
 #include <sys/mman.h>
 #include <stdio.h>

tools/testing/selftests/cgroup/test_kmem.c

@@ -1,4 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
 #include <linux/limits.h>
 #include <fcntl.h>
 #include <stdio.h>

tools/testing/selftests/cgroup/test_memcontrol.c

@@ -1,4 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#define _GNU_SOURCE
+
 #include <linux/limits.h>
 #include <linux/oom.h>
 #include <fcntl.h>

tools/testing/selftests/cgroup/test_zswap.c

@@ -1,4 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
 #include <linux/limits.h>
 #include <unistd.h>
 #include <stdio.h>