cve-update-db-native: add an index on the CVE ID column

Create an index on the PRODUCTS table which contains a row for each CPE,
drastically increasing the performance of lookups for a specific CVE.

(From OE-Core rev: b4048b05)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>