ART: General-case negation in boolean simplifier

Code transformations on the HGraph may optimize out the condition
instruction of an If and replace it with a boolean value. In such
case, the boolean simplifier would not know how to negate the
condition and would fail. This patch implements negation in this
general case with 'equals 0' as a substitute for the non-existing
boolean Not instruction.

Bug: 19992954
Change-Id: I152036fcc6bbecccc767d3024a5c060177597d88