Fix select decoding for glibc in _FORTIFY_SOURCE mode

glibc in _FORTIFY_SOURCE mode raises SIGABRT when descriptor greater
or equal to FD_SETSIZE is passed to FD_ISSET.  Select family syscalls,
however, can legitimately accept such descriptors.  To overcome this
limitation, we have to replace FD_ISSET with an equivalent that imposes
no such restrictions.

* desc.c (fd_isset): New function.
(decode_select): Use it instead of FD_ISSET.
1 file changed