Sync with 2.16.5

* maint-2.16:
  Git 2.16.5
  Git 2.15.3
  Git 2.14.5
  submodule-config: ban submodule paths that start with a dash
  submodule-config: ban submodule urls that start with dash
  submodule--helper: use "--" to signal end of clone options

builtin/submodule--helper.c

@@ -1078,6 +1078,7 @@ static int clone_submodule(const char *path, const char *gitdir, const char *url
 	if (gitdir && *gitdir)
 		argv_array_pushl(&cp.args, "--separate-git-dir", gitdir, NULL);
 
+	argv_array_push(&cp.args, "--");
 	argv_array_push(&cp.args, url);
 	argv_array_push(&cp.args, path);