add PKG_CPE_ID ids to package and tools

CPE ids helps to tracks CVE in packages.
https://cpe.mitre.org/specification/

Thanks to swalker for CPE to package mapping and
keep tracking CVEs.

Acked-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>

package/libs/libjson-c/Makefile

@@ -19,6 +19,7 @@ PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_SOURCE_SUBDIR)
 
 PKG_LICENSE:=MIT
 PKG_LICENSE_FILES:=COPYING
+PKG_CPE_ID:=cpe:/a:json-c_project:json-c
 
 PKG_FIXUP:=autoreconf
 PKG_INSTALL:=1