Merge branch 'pt/xdg-config-path' into maint

Code clean-up for xdg configuration path support. * pt/xdg-config-path: path.c: remove home_config_paths() git-config: replace use of home_config_paths() git-commit: replace use of home_config_paths() credential-store.c: replace home_config_paths() with xdg_config_home() dir.c: replace home_config_paths() with xdg_config_home() attr.c: replace home_config_paths() with xdg_config_home() path.c: implement xdg_config_home() t0302: "unreadable" test needs POSIXPERM t0302: test credential-store support for XDG_CONFIG_HOME git-credential-store: support XDG_CONFIG_HOME git-credential-store: support multiple credential files