classes/buildhistory: record LICENSE

Buildhistory stores various bits of information at both recipe
and package level, while there is an associated license manifest
directory tree it would require additional scripting to extract
that information.

(From OE-Core rev: 909bafef282f00dd4a83fab0569885e9788a4ed9)

Signed-off-by: Saul Wold <saul.wold@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>