Re-evaluate the pathmap if there's a recovery variant in play

Chances are the recovery location has changed, so rebuild the pathmap
to compensate. This lets the variable be defined in BoardConfig files
instead of the global environment

Change-Id: I87c23a452656ffa7817711796c17f79e30465756
Merge branch 'cm-11.0' of https://github.com/Cyanogenmod/android_build into cm-11.0