* src/gpgrt-int.h (_gpgrt_close_all_fds): Fix function declaration.
* src/spawn-posix.c (USE_GET_MAX_FDS): Define when closefrom is not
available.
(get_max_fds): Add an argument of FALLBACK_MAX_FDS.
(_gpgrt_close_all_fds, my_exec, spawn_detached): Likewise.
(_gpgrt_process_spawn): [USE_GET_MAX_FDS && _SC_OPEN_MAX]: It's a
parent process which calls sysconf.