package/libunwind: add LIBUNWIND_CPE_ID_VENDOR

cpe:2.3:a:libunwind_project:libunwind is a valid CPE identifier for this
package:

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

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit f1bfc0d0543593f27dda4666c9ec57cb54ffb4e8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libunwind/libunwind.mk

@@ -9,6 +9,7 @@ LIBUNWIND_SITE = http://download.savannah.gnu.org/releases/libunwind
 LIBUNWIND_INSTALL_STAGING = YES
 LIBUNWIND_LICENSE_FILES = COPYING
 LIBUNWIND_LICENSE = MIT
+LIBUNWIND_CPE_ID_VENDOR = libunwind_project
 LIBUNWIND_AUTORECONF = YES
 
 LIBUNWIND_CONF_OPTS = \