setopt: add CURLOPT_CURLU

Allows an application to pass in a pre-parsed URL via a URL handle.

Closes #3227

include/curl/curl.h

@@ -1872,6 +1872,9 @@ typedef enum {
   /* Time in ms between connection upkeep calls for long-lived connections. */
   CINIT(UPKEEP_INTERVAL_MS, LONG, 281),
 
+  /* Specify URL using CURL URL API. */
+  CINIT(CURLU, OBJECTPOINT, 282),
+
   CURLOPT_LASTENTRY /* the last unused */
 } CURLoption;
 

include/curl/typecheck-gcc.h

@@ -363,6 +363,7 @@ _CURL_WARNING(_curl_easy_getinfo_err_curl_off_t,
    (option) == CURLOPT_SSL_CTX_DATA ||                                        \
    (option) == CURLOPT_WRITEDATA ||                                           \
    (option) == CURLOPT_RESOLVER_START_DATA ||                                 \
+   (option) == CURLOPT_CURLU ||                                               \
    0)
 
 /* evaluates to true if option takes a POST data argument (void* or char*) */