Fix optimizer with regards to INVALID instruction.

libevmasm/PeepholeOptimiser.cpp

@@ -199,6 +199,7 @@ struct UnreachableCode
 			it[0] != Instruction::JUMP &&
 			it[0] != Instruction::RETURN &&
 			it[0] != Instruction::STOP &&
+			it[0] != Instruction::INVALID &&
 			it[0] != Instruction::SUICIDE
 		)
 			return false;

libevmasm/SemanticInformation.cpp

@@ -118,6 +118,7 @@ bool SemanticInformation::altersControlFlow(AssemblyItem const& _item)
 	case Instruction::RETURN:
 	case Instruction::SUICIDE:
 	case Instruction::STOP:
+	case Instruction::INVALID:
 		return true;
 	default:
 		return false;