[ConstraintSystem] Convert TypeVariableOptions enum to String for use in printing.
[ConstraintSystem] Convert TypeVariableOptions enum to String for use in printing.

JGiola/swift,glessard/swift,benlangmuir/swift,glessard/swift,apple/swift,apple/swift,benlangmuir/swift,roambotics/swift,benlangmuir/swift,apple/swift,JGiola/swift,apple/swift,roambotics/swift,apple/swift,roambotics/swift,glessard/swift,glessard/swift,roambotics/swift,JGiola/swift,JGiola/swift,benlangmuir/swift,apple/swift,glessard/swift,JGiola/swift,glessard/swift,JGiola/swift,benlangmuir/swift,benlangmuir/swift,roambotics/swift,roambotics/swift