build: Add alternate recovery to pathmap

Change-Id: I2827ace9729b6af8d5b4e637374ccd1e5902dd55
Fix the alternate recovery inclusion logic

Change-Id: Ifb59d61dae44dd639d7f891dc57bb326b06b1118
build: core: Parameterize recovery with a variant

Include extra vendor config early.  If RECOVERY_VARIANT is set, use it
to look for the recovery in an alternate path.

Change-Id: Iba54f0746d728c0dfeeb67b4d3166d5e25b1b5d7
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
display RECOVERY_VARIANT in build info

ps2:
  fix logic for inclusion of different recovery variants

Change-Id: If95fd668742ab3062e125168c75da29002502939