Use 'dst' as the CBRANCH condition register

See issue #43

src/assembly_generator_x86.hpp

@@ -89,6 +89,6 @@ namespace randomx {
 
 		static InstructionGenerator engine[256];
 		std::stringstream asmCode;
-		RegisterUsage registerUsage[RegistersCount];
+		int registerUsage[RegistersCount];
 	};
 }