bitbake: tinfoil: add a means of enabling variable history tracking

bitbake: tinfoil: add a means of enabling variable history tracking

Unfortunately it seems like the external use of the cooker
enableDataTracking() function broke at some point since the code that
reads it now runs within BBCooker's constructor. Since this now has to
be done early, add a parameter to Tinfoil's constructor to allow
enabling variable history tracking.

Fixes [YOCTO #6676].

(Bitbake rev: a9439b136f55f3f0e80ff053cd3b159da69ba362)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>