hooks: remove implicit dependency on the_repository

We implicitly depend on `the_repository` in our hook subsystem because
we use `strbuf_git_path()` to compute hook paths. Remove this dependency
by accepting a `struct repository` as parameter instead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -1960,5 +1960,5 @@ int run_commit_hook(int editor_is_used, const char *index_file,
 	va_end(args);
 
 	opt.invoked_hook = invoked_hook;
-	return run_hooks_opt(name, &opt);
+	return run_hooks_opt(the_repository, name, &opt);
 }