lxc: remove duplicate header files

"#include vircgroup.h" appears in both lxc_cgroup.h and
lxc_cgroup.c, and lxc_cgroup.c contains lxc_cgroup.h,
so remove the duplicate declarations.
Signed-off-by: NMao Zhongyi <maozhongyi@cmss.chinamobile.com>
Signed-off-by: NZhang Shengju <zhangshengju@cmss.chinamobile.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/lxc/lxc_cgroup.c

@@ -27,7 +27,6 @@
 #include "virerror.h"
 #include "virlog.h"
 #include "viralloc.h"
-#include "vircgroup.h"
 #include "virstring.h"
 #include "virsystemd.h"