Add strict-export option

This option is used to specify a filename which needs to be present in
the repositories found during `scan-path` processing. By setting this
option to 'git-daemon-export-ok', only repositories explicitly marked
for git daemon export will be included in the cgit configuration.

Signed-off-by: Felix Hanley <felix@seconddrawer.com.au>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.h

@@ -176,6 +176,7 @@ struct cgit_config {
 	char *script_name;
 	char *section;
 	char *virtual_root;
+	char *strict_export;
 	int cache_size;
 	int cache_dynamic_ttl;
 	int cache_max_create_time;