package/libminiupnpc: add CPE variables

package/libminiupnpc: add CPE variables

cpe:2.3:a:miniupnp_project:miniupnpc is a valid CPE identifier for this
package:

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

Split the _VERSION into the traditional major/minor separation, even
though it is not strictly speaking major/minor. This allows re-using for
the CPE versioning.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr:
  - inverse the split: rather than defining _VERSION based on the CPE
    values, split the _VERSION and use that to define the CPE variables
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>