They take a pointer to a free-list used for hashlinks so the hashlink
pools can be per-thread. However, hash tables that are not updated are
always thread-safe, so this affects only updates. progs_t has been set
up such that it is easy for multiple progs within one thread can share
hashlinks.
While the key escape sequences are xterm-specific, they are only the
default and preliminary provision has been made for overriding them.
However, no override mechanism has been implemented beyond using dynamic
table lookup.
I'd left qwaq-curses running overnight and found it locked up: both
threads were looping because pthread_cond_timedwait was returning
EINVAL. Thus bail if anything other than 0 is returned, and try to
ensure tv_nsec is in the range 0..999999999
