tar: filter CVEs using vendor name

Recently a number of CVEs have been logged against a nodejs project
called "node-tar". These appear as false positives against the GNU tar
being built by Yocto. Some of these have been manually excluded using
CVE_CHECK_WHITELIST.

To avoid this problem, use the vendor name (in addition to package name)
for filtering CVEs. The syntax for this is:
  CVE_PRODUCT = "vendor:package"
When not specified, the vendor defaults to "%" which matches anything.

Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>