bitbake.conf: Exclude WORKDIR changes from sstate checksums
The layout of stamp files ensures that changes to WORKDIR mean recipes get rebuilt correctly.
Since WORKDIR usually contains MULTIMACH_TARGET_SYS and that depends on tune variables,
including WORKDIR in sstate checksums adds a lot of noise to the system for what amounts to
no gain.
On the other hand, removing it reduces noise, reduces the size of the siginfo files and
reduces the amount of processing bitbake has to do. It therefore seems like dropping it
from the checksums is an all around win.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
