package/c-icap: set C_ICAP_CPE_ID_VALID

cpe:2.3:a:c-icap_project:c-icap is a valid CPE identifier for this
package:

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



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