package/poppler: add POPPLER_CPE_ID_VENDOR

cpe:2.3:a:freedesktop:poppler is a valid CPE identifier for this
package:

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

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

package/poppler/poppler.mk

@@ -10,6 +10,7 @@ POPPLER_SITE = http://poppler.freedesktop.org
 POPPLER_DEPENDENCIES = fontconfig host-pkgconf
 POPPLER_LICENSE = GPL-2.0+
 POPPLER_LICENSE_FILES = COPYING
+POPPLER_CPE_ID_VENDOR = freedesktop
 POPPLER_INSTALL_STAGING = YES
 
 POPPLER_CONF_OPTS = \