Adjust to recent Gnulib changes
The latest Gnulib merge brought in free-posix, which causes 'free' to preserve errno. This lets us simplify some Emacs code that calls 'free'. * admin/merge-gnulib (GNULIB_MODULES): Add free-posix. This module is pulled in by canonicalize-lgpl anyway, so we might as well rely on it. * lib-src/emacsclient.c (get_current_dir_name): Sync better with src/sysdep.c. * lib-src/etags.c (process_file_name, etags_mktmp): * lib-src/update-game-score.c (unlock_file): * src/fileio.c (file_accessible_directory_p): * src/sysdep.c (get_current_dir_name_or_unreachable): Simplify by assuming that 'free' preserves errno. * src/alloc.c (malloc_unblock_input): Preserve errno, so that xfree preserves errno. * src/sysdep.c (get_current_dir_name_or_unreachable): Simplify by using strdup instead of malloc+memcpy. No need for realloc (and the old code leaked memory anyway on failure); just use free+malloc.