package/libass: set LIBASS_CPE_ID_VALID

cpe:2.3:a:libass_project:libass is a valid CPE identifier for this
package:

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

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libass/libass.mk

@@ -12,6 +12,7 @@ LIBASS_SITE = https://github.com/libass/libass/releases/download/$(LIBASS_VERSIO
 LIBASS_INSTALL_STAGING = YES
 LIBASS_LICENSE = ISC
 LIBASS_LICENSE_FILES = COPYING
+LIBASS_CPE_ID_VALID = YES
 LIBASS_DEPENDENCIES = \
 	host-pkgconf \
 	freetype \