curl_version_info.3: fixed the 'protocols' variable type

Reported-by: John Marshall
Bug: #225

docs/libcurl/curl_version_info.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -57,7 +57,7 @@ typedef struct {
   char *ssl_version;        /* human readable string */
   long ssl_version_num;     /* not used, always zero */
   const char *libz_version; /* human readable string */
-  const char **protocols;   /* list of protocols */
+  const char * const *protocols; /* protocols */
 
   /* when 'age' is 1 or higher, the members below also exist: */
   const char *ares;         /* human readable string */