url: Fixed connection re-use when using different log-in credentials

In addition to FTP, other connection based protocols such as IMAP, POP3,
SMTP, SCP, SFTP and LDAP require a new connection when different log-in
credentials are specified. Fixed the detection logic to include these
other protocols.

Bug: http://curl.haxx.se/docs/adv_20140326A.html

lib/http.c

@@ -145,7 +145,7 @@ const struct Curl_handler Curl_handler_https = {
   ZERO_NULL,                            /* readwrite */
   PORT_HTTPS,                           /* defport */
   CURLPROTO_HTTP | CURLPROTO_HTTPS,     /* protocol */
-  PROTOPT_SSL                           /* flags */
+  PROTOPT_SSL | PROTOPT_CREDSPERREQUEST /* flags */
 };
 #endif
 

lib/url.c

@@ -3060,9 +3060,10 @@ ConnectionExists(struct SessionHandle *data,
           continue;
       }
 
-      if((needle->handler->protocol & CURLPROTO_FTP) || wantNTLMhttp) {
-        /* This is FTP or HTTP+NTLM, verify that we're using the same name
-           and password as well */
+      if((!(needle->handler->flags & PROTOPT_CREDSPERREQUEST)) ||
+         wantNTLMhttp) {
+        /* This protocol requires credentials per connection or is HTTP+NTLM,
+           so verify that we're using the same name and password as well */
         if(!strequal(needle->user, check->user) ||
            !strequal(needle->passwd, check->passwd)) {
           /* one of them was different */

lib/urldata.h

@@ -795,6 +795,8 @@ struct Curl_handler {
                                       gets a default */
 #define PROTOPT_NOURLQUERY (1<<6)   /* protocol can't handle
                                         url query strings (?foo=bar) ! */
+#define PROTOPT_CREDSPERREQUEST (1<<7) /* requires login creditials per request
+                                          as opposed to per connection */
 
 
 /* return the count of bytes sent, or -1 on error */