Implement vertex swizzle

src/graphics/shader/recompiler/ShaderDecoder.h

@@ -639,6 +639,8 @@ struct Instruction {
 	bool           slc                                          = false;
 	bool           idxen                                        = false;
 	bool           offen                                        = false;
+	// V_CMPX writes the comparison result to its normal scalar destination and EXEC.
+	bool           compare_exec                                 = false;
 	int32_t        branch_offset                                = 0;
 	uint32_t       branch_target                                = 0;
 	struct {