Keep the upload byte counter in an curl_off_t, not an int. 32bits is not

enough. This is most likely the bug Jean-Louis Lemaire reported that makes
2GB FTP uploads to report error when completed.
Also padded comments to get them aligned again, only for visibility.

lib/urldata.h

@@ -339,14 +339,14 @@ struct hostname {
 
 struct Curl_transfer_keeper {
   curl_off_t bytecount;         /* total number of bytes read */
-  int writebytecount;           /* number of bytes written */
+  curl_off_t writebytecount;    /* number of bytes written */
   struct timeval start;         /* transfer started at this time */
   struct timeval now;           /* current time */
   bool header;	                /* incoming data has HTTP header */
   enum {
     HEADER_NORMAL,              /* no bad header at all */
-    HEADER_PARTHEADER,  /* part of the chunk is a bad header, the rest is
-                           normal data */
+    HEADER_PARTHEADER,          /* part of the chunk is a bad header, the rest
+                                   is normal data */
     HEADER_ALLBAD               /* all was believed to be header */
   } badheader;		        /* the header was deemed bad and will be
                                    written as body */
@@ -383,7 +383,6 @@ struct Curl_transfer_keeper {
   z_stream z;			/* State structure for zlib. */
 #endif
 
-  /* for the low speed checks: */
   time_t timeofdoc;
   long bodywrites;