Merge branch 'ab/config-multi-and-nonbool'

Assorted config API updates.

* ab/config-multi-and-nonbool:
  for-each-repo: with bad config, don't conflate <path> and <cmd>
  config API: add "string" version of *_value_multi(), fix segfaults
  config API users: test for *_get_value_multi() segfaults
  for-each-repo: error on bad --config
  config API: have *_multi() return an "int" and take a "dest"
  versioncmp.c: refactor config reading next commit
  config API: add and use a "git_config_get()" family of functions
  config tests: add "NULL" tests for *_get_value_multi()
  config tests: cover blind spots in git_die_config() tests

submodule.c

@@ -275,8 +275,7 @@ int is_tree_submodule_active(struct repository *repo,
 	free(key);
 
 	/* submodule.active is set */
-	sl = repo_config_get_value_multi(repo, "submodule.active");
-	if (sl) {
+	if (!repo_config_get_string_multi(repo, "submodule.active", &sl)) {
 		struct pathspec ps;
 		struct strvec args = STRVEC_INIT;
 		const struct string_list_item *item;