ART: Implement HBooleanNot instruction

Optimizations simplifying operations on boolean values (boolean
simplifier, instruction simplifier) can benefit from having a special
HInstruction for negating booleans in order to perform more transforms
and produce faster machine code.

This patch implements HBooleanNot as 'x xor 1', assuming that booleans
are 1-bit integers and allowing for a single-instruction negation on
all supported platforms.

Change-Id: I33a2649c1821255b18a86ca68ed16416063c739f