package/jsoncpp: set JSONCPP_CPE_ID_VALID

cpe:2.3:a:jsoncpp_project:jsoncpp is a valid CPE identifier for this
package:

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

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

package/jsoncpp/jsoncpp.mk

@@ -8,6 +8,7 @@ JSONCPP_VERSION = 1.9.4
 JSONCPP_SITE = $(call github,open-source-parsers,jsoncpp,$(JSONCPP_VERSION))
 JSONCPP_LICENSE = Public Domain or MIT
 JSONCPP_LICENSE_FILES = LICENSE
+JSONCPP_CPE_ID_VALID = YES
 JSONCPP_INSTALL_STAGING = YES
 JSONCPP_CONF_OPTS = -Dtests=false