insane.bbclass: add package specific skips to sstate hash
The bbclass currently adds INSANE_SKIP to the sstate hash dependencies
however the package specific skips such as INSANE_SKIP_${PN} are
not added automatically because of how the class references them.
This causes the problem that modifying INSANE_SKIP_${PN} does not
invalidate the sstate cache and can mask build breaking warnings.
Add an anonymous python snippet to explicitly include these additional
relevant skips to the sstate hash.
Singed-off-by: Michael Ho <Michael.Ho@bmw.de> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
