Updated user.mk to have regression testing option off by default.
Updated user.mk to have regression testing option off by default.

UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4