package/gnuplot: set GNUPLOT_CPE_ID_VALID

cpe:2.3:a:gnuplot_project:gnuplot is a valid CPE identifier for this
package:

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

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gnuplot/gnuplot.mk

@@ -8,6 +8,7 @@ GNUPLOT_VERSION = 5.4.1
 GNUPLOT_SITE = http://downloads.sourceforge.net/project/gnuplot/gnuplot/$(GNUPLOT_VERSION)
 GNUPLOT_LICENSE = gnuplot license (open source)
 GNUPLOT_LICENSE_FILES = Copyright
+GNUPLOT_CPE_ID_VALID = YES
 
 GNUPLOT_AUTORECONF = YES