package/log4cxx: add CPE ID

apache:log4cxx is a valid CPE ID:
https://nvd.nist.gov/products/cpe/detail/BFD3FB55-EE37-4297-BB3F-DD0A051DAD65?namingFormat=2.3&orderBy=CPEURI&keyword=log4cxx&status=FINAL

Signed-off-by: Daniel Lang <dalang@gmx.at>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 8ca41303efbada05fa0acf577ca86bd8f1a7eb15)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/log4cxx/log4cxx.mk

@@ -10,6 +10,7 @@ LOG4CXX_SOURCE = apache-log4cxx-$(LOG4CXX_VERSION).tar.gz
 LOG4CXX_INSTALL_STAGING = YES
 LOG4CXX_LICENSE = Apache-2.0
 LOG4CXX_LICENSE_FILES = LICENSE
+LOG4CXX_CPE_ID_VENDOR = apache
 
 LOG4CXX_CONF_OPTS = \
 	-DAPR_CONFIG_EXECUTABLE=$(STAGING_DIR)/usr/bin/apr-1-config \