Add parameter to adjust max message length in log listings

The parameter "max-message-length" can be specified in cgitrc, default value
is 60.

This affects the log message shown in repo summary and shortlog.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.h

@@ -52,6 +52,8 @@ extern int cgit_cache_dynamic_ttl;
 extern int cgit_cache_static_ttl;
 extern int cgit_cache_max_create_time;
 
+extern int cgit_max_msg_len;
+
 extern char *cgit_repo_name;
 extern char *cgit_repo_desc;
 extern char *cgit_repo_owner;