Do not provide a default value for module-link

The old default value was an abomination which never should have been
allowed to see the light of day.

This patch removes the default, which is a backwards incompatible change
with low probability of causing anyone any real trouble (a repo with
submodules, displayed by cgit using the default value of `module-link`,
is very unlikely to actually generate working links).

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

cgit.c

@@ -343,7 +343,6 @@ static void prepare_context(struct cgit_context *ctx)
 	ctx->cfg.max_repodesc_len = 80;
 	ctx->cfg.max_blob_size = 0;
 	ctx->cfg.max_stats = 0;
-	ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
 	ctx->cfg.project_list = NULL;
 	ctx->cfg.renamelimit = -1;
 	ctx->cfg.remove_suffix = 0;