There are some issues in sstate which can't be handled by file removal
alone. Currently there is no way to execute a command against sstate and
doing so is potentially problematic for things like dependencies. This
patch adds a mechanism where any "postrm" script is executed if its present
allowing some openjade/sgml issues to be resolved.
[YOCTO #8273]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
