urlapi: CURLU_PUNY2IDN - convert from punycode to IDN name

Asssisted-by: Jay Satiro
Closes #11655

include/curl/urlapi.h

@@ -97,6 +97,7 @@ typedef enum {
                                            scheme is unknown. */
 #define CURLU_ALLOW_SPACE (1<<11)       /* Allow spaces in the URL */
 #define CURLU_PUNYCODE (1<<12)          /* get the host name in punycode */
+#define CURLU_PUNY2IDN (1<<13)          /* punycode => IDN conversion */
 
 typedef struct Curl_URL CURLU;