* vfs/fish.c (fish_directory_timeout): Define new global variable.
(FISH_DIRECTORY_TIMEOUT): Eliminate - this macro is not used
anywhere.
(fish_dir_load): Use `fish_directory_timeout' to calculate the
expiration time of a newly created directory entries.
* src/setup.c [USE_NETCODE]: Include fish.h .
(int_options) [USE_NETCODE]: Add support for user configurable
expiration timeout of FISH directory cache entries.
* doc/mc.1.in: Document `fish_directory_timeout'.