package/graphicsmagick: add GRAPHICSMAGICK_CPE_ID_VENDOR

cpe:2.3:a:graphicsmagick:graphicsmagick is a valid CPE identifier for
this package:

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

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/graphicsmagick/graphicsmagick.mk

@@ -9,6 +9,7 @@ GRAPHICSMAGICK_SOURCE = GraphicsMagick-$(GRAPHICSMAGICK_VERSION).tar.xz
 GRAPHICSMAGICK_SITE = https://downloads.sourceforge.net/project/graphicsmagick/graphicsmagick/$(GRAPHICSMAGICK_VERSION)
 GRAPHICSMAGICK_LICENSE = MIT
 GRAPHICSMAGICK_LICENSE_FILES = Copyright.txt
+GRAPHICSMAGICK_CPE_ID_VENDOR = graphicsmagick
 
 GRAPHICSMAGICK_INSTALL_STAGING = YES
 GRAPHICSMAGICK_CONFIG_SCRIPTS = GraphicsMagick-config GraphicsMagickWand-config