add support for --enc2-test knob to build the ENC2 tests upon request
add support for --enc2-test knob to build the ENC2 tests upon request

Change-Id: Ib726608829c9e2c099f4a9a48a623e4bfd69003a
(cherry picked from commit e1b2dbbe5c75d183a09ba4c73f1e399c47a46e59)

intelxed/xed,intelxed/xed,intelxed/xed,intelxed/xed