package/libnspr: add CPE variables

cpe:2.3:a:mozilla:netscape_portable_runtime is a valid CPE identifier
for this package:

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



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>