vircgrouptest: add detect mounts test for cgroup v2

Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

tests/vircgroupdata/unified.cgroups

+#subsys_name	hierarchy	num_cgroups	enabled
+cpuset      0       1       1
+cpu         0       1       1
+cpuacct     0       1       1
+blkio       0       1       1
+memory      0       1       1
+devices     0       1       1
+freezer     0       1       1
+net_cls     0       1       1
+perf_event  0       1       1
+net_prio    0       1       1
+hugetlb     0       1       1
+pids        0       1       1

tests/vircgroupdata/unified.mounts

+sysfs /sys sysfs rw,seclabel,nosuid,nodev,noexec,relatime 0 0
+proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
+devtmpfs /dev devtmpfs rw,seclabel,nosuid,size=1009844k,nr_inodes=252461,mode=755 0 0
+securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /dev/shm tmpfs rw,seclabel,nosuid,nodev 0 0
+devpts /dev/pts devpts rw,seclabel,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
+tmpfs /run tmpfs rw,seclabel,nosuid,nodev,mode=755 0 0
+cgroup2 /not/really/sys/fs/cgroup cgroup2 rw,seclabel,nosuid,nodev,noexec,relatime,nsdelegate 0 0
+pstore /sys/fs/pstore pstore rw,seclabel,nosuid,nodev,noexec,relatime 0 0
+bpf /sys/fs/bpf bpf rw,nosuid,nodev,noexec,relatime,mode=700 0 0
+configfs /sys/kernel/config configfs rw,relatime 0 0
+/dev/vda2 / ext4 rw,seclabel,relatime 0 0
+selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
+debugfs /sys/kernel/debug debugfs rw,seclabel,relatime 0 0
+hugetlbfs /dev/hugepages hugetlbfs rw,seclabel,relatime,pagesize=2M 0 0
+systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=40,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=14586 0 0
+mqueue /dev/mqueue mqueue rw,seclabel,relatime 0 0
+tmpfs /tmp tmpfs rw,seclabel,nosuid,nodev 0 0
+sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0
+tmpfs /run/user/0 tmpfs rw,seclabel,nosuid,nodev,relatime,size=204000k,mode=700 0 0

tests/vircgroupdata/unified.parsed

+cpu          <null>
+cpuacct      <null>
+cpuset       <null>
+memory       <null>
+devices      <null>
+freezer      <null>
+blkio        <null>
+net_cls      <null>
+perf_event   <null>
+name=systemd <null>
+unified      /not/really/sys/fs/cgroup

tests/vircgroupdata/unified.self.cgroup

+0::/

tests/vircgrouptest.c

@@ -899,6 +899,9 @@ mymain(void)
     DETECT_MOUNTS("all-in-one");
     DETECT_MOUNTS_FAIL("no-cgroups");
     DETECT_MOUNTS("kubevirt");
+    fakerootdir = initFakeFS("unified", NULL);
+    DETECT_MOUNTS("unified");
+    cleanupFakeFS(fakerootdir);
 
     fakerootdir = initFakeFS(NULL, "systemd");
     if (virTestRun("New cgroup for self", testCgroupNewForSelf, NULL) < 0)