package/graphite2: add GRAPHITE2_CPE_ID_VENDOR

cpe:2.3:a:sil:graphite2 is a valid CPE identifier for this package:

  https://nvd.nist.gov/products/cpe/search/results?namingFormat=2.3&keyword=cpe%3A2.3%3Aa%3Asil%3Agraphite2

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/graphite2/graphite2.mk

@@ -11,6 +11,7 @@ GRAPHITE2_SITE = \
 GRAPHITE2_INSTALL_STAGING = YES
 GRAPHITE2_LICENSE = LGPL-2.1+
 GRAPHITE2_LICENSE_FILES = LICENSE
+GRAPHITE2_CPE_ID_VENDOR = sil
 
 # Avoid building docs and tests to save time
 define GRAPHITE2_DISABLE_TESTS_DOC