ui-tree.c: add support for path-selected submodule links

The current 'repo.module-link' option is sufficient when all gitlinks
in a repository can be converted to commit links in a uniform way, but
not when different submodules/paths needs different settings.

This patch adds support for 'repo.module-link.<path>', which will be
used for linking to submodules at paths matching one such entry.

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

ui-shared.h

@@ -51,6 +51,9 @@ extern void cgit_self_link(char *name, const char *title,
 			   const char *class, struct cgit_context *ctx);
 extern void cgit_object_link(struct object *obj);
 
+extern void cgit_submodule_link(const char *class, char *path,
+				const char *rev);
+
 extern void cgit_print_error(const char *msg);
 extern void cgit_print_date(time_t secs, const char *format, int local_time);
 extern void cgit_print_age(time_t t, time_t max_relative, const char *format);