package/libcgroup: add LIBCGROUP_CPE_ID_VENDOR

cpe:2.3:a:libcgroup_project:libcgroup is a valid CPE identifier for this
package:

  https://nvd.nist.gov/products/cpe/search/results?namingFormat=2.3&keyword=cpe%3A2.3%3Aa%3Alibcgroup_project%3Alibcgroup

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/libcgroup/libcgroup.mk

@@ -9,6 +9,7 @@ LIBCGROUP_SOURCE = libcgroup-$(LIBCGROUP_VERSION).tar.bz2
 LIBCGROUP_SITE = https://github.com/libcgroup/libcgroup/releases/download/v$(LIBCGROUP_VERSION)
 LIBCGROUP_LICENSE = LGPL-2.1
 LIBCGROUP_LICENSE_FILES = COPYING
+LIBCGROUP_CPE_ID_VENDOR = libcgroup_project
 LIBCGROUP_DEPENDENCIES = host-bison host-flex
 LIBCGROUP_INSTALL_STAGING = YES