package/diffutils: add DIFFUTILS_CPE_ID_VENDOR

cpe:2.3:a:gnu:diffutils is a valid identifier for
this package:
https://nvd.nist.gov/products/cpe/search/results?namingFormat=2.3&keyword=diffutils

Signed-off-by: Clément Ramirez <clement.ramirez@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/diffutils/diffutils.mk

@@ -10,6 +10,7 @@ DIFFUTILS_SITE = $(BR2_GNU_MIRROR)/diffutils
 DIFFUTILS_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES)
 DIFFUTILS_LICENSE = GPL-3.0+
 DIFFUTILS_LICENSE_FILES = COPYING
+DIFFUTILS_CPE_ID_VENDOR = gnu
 
 # Since glibc >= 2.26, don't try to use getopt_long replacement bundled
 # with diffutils. It will conflict with the one from glibc.